research covid 19 vaccine

COVID-19 vaccines: Get the facts

Looking to get the facts about COVID-19 vaccines? Here's what you need to know about the different vaccines and the benefits of getting vaccinated.

As the coronavirus disease 2019 (COVID-19) continues to cause illness, you might have questions about COVID-19 vaccines. Find out about the different types of COVID-19 vaccines, how they work, the possible side effects, and the benefits for you and your family.

COVID-19 vaccine benefits

What are the benefits of getting a covid-19 vaccine.

Staying up to date with a COVID-19 vaccine can:

• Help prevent serious illness and death due to COVID-19 for both children and adults.
• Help prevent you from needing to go to the hospital due to COVID-19 .
• Boost your body's protection, also called immunity, against catching the virus that causes COVID-19 .
• Be a safer way to protect yourself compared to getting sick with the virus that causes COVID-19 .

How much protection a COVID-19 vaccine gives depends on different factors. Factors that can affect how much you're protected with a vaccine can include your age, if you've had COVID-19 before or if you have medical conditions such as cancer.

How well a COVID-19 vaccine protects you also depends on how the virus that causes COVID-19 changes and what variants the vaccine protects against. Your level of protection also depends on timing, such as when you got the shot.

Talk to your healthcare team about how you can stay up to date with COVID-19 vaccines.

Should I get the COVID-19 vaccine even if I've already had COVID-19?

Yes. After you've had COVID-19 , getting vaccinated can boost your body's protection against catching the virus that causes COVID-19 another time.

Getting COVID-19 or getting a COVID-19 vaccination gives you protection, also called immunity, from being infected again with the virus that causes COVID-19 . But over time, that protection seems to fade. Getting COVID-19 again may cause serious illness or medical complications, especially for people with risk factors for severe COVID-19 .

Researchers continue to study what happens when someone has COVID-19 a second time. Reinfections are generally milder than the first infection. But severe illness can still happen. Some people may see their risk of having to go to the hospital and having medical problems such as diabetes go up with each COVID-19 infection.

Research has found that people who have had COVID-19 and then have had all of the suggested COVID-19 vaccinations are less likely to be treated in the hospital due to COVID-19 than people who are not vaccinated or who haven't had all the suggested shots. This protection wears off in the months after getting the vaccine.

Also, because the virus that causes COVID-19 can change, also called mutate, a vaccination with the latest strain, or variant, that is spreading or expected to spread can help keep you from getting sick again.

Safety and side effects of COVID-19 vaccines

What covid-19 vaccines have been authorized or approved.

The COVID-19 vaccines available in the United States are:

• 2023-2024 Pfizer-BioNTech COVID-19 vaccine, available for people age 6 months and older.
• 2023-2024 Moderna COVID-19 vaccine, available for people age 6 months and older.
• 2023-2024 Novavax COVID-19 vaccine, available for people age 12 years and older.

In general, people age 5 and older with typical immune systems can get any vaccine that is approved or authorized for their age. They usually don't need to get the same vaccine each time.

Some people should get all their vaccine doses from the same vaccine maker, including:

• Children ages 6 months to 4 years.
• People age 5 years and older with weakened immune systems.
• People age 12 and older who have had one shot of the Novavax vaccine should get the second Novavax shot in the two-dose series.

Talk to your healthcare professional if you have any questions about the vaccines for you or your child. Your healthcare team can help you if:

• The vaccine you or your child got earlier isn't available.
• You don't know which vaccine you or your child received.
• You or your child started a vaccine series but couldn't finish it due to side effects.

At the start of the COVID-19 pandemic, COVID-19 vaccines were needed right away. But the U.S. Food and Drug Administration's (FDA's) vaccine approval process can take years.

To provide vaccines sooner, the FDA gave emergency use authorization to COVID-19 vaccines based on less data than is typically required. But the data still has to show that the vaccines are safe and effective.

In August 2022, the FDA authorized an update to the Moderna and the Pfizer-BioNTech COVID-19 vaccines. Both included the original and omicron variants of the virus that causes COVID-19 .

In June 2023, the FDA directed vaccine makers to update COVID-19 vaccines. The vaccines were changed to target a strain of the virus that causes COVID-19 called XBB.1.5.

In September and October 2023, the FDA authorized the use of the updated 2023-2024 COVID-19 vaccines made by Novavax, Moderna and Pfizer-BioNTech.

Vaccines with FDA emergency use authorization or approval include:

2023-2024 Pfizer-BioNTech COVID-19 vaccine. This vaccine was first tested against the original strain of the COVID-19 virus. That strain began spreading at the end of 2019. In December 2020, the Pfizer-BioNTech COVID-19 vaccine two-dose series was found to be both safe and 91% to 95% effective in preventing COVID-19 infection in people age 18 and older. This data helped predict how well the vaccines would work for younger people. The effectiveness varied by age.

The Pfizer-BioNTech vaccine is approved under the name Comirnaty for people age 12 and older. It is authorized for people age 6 months to 11 years. The number of shots in this vaccination series varies based on a person's age and COVID-19 vaccination history.

2023-2024 Moderna COVID-19 vaccine. This vaccine also was first tested against the original strain of the virus that causes COVID-19 . In December 2020, the Moderna COVID-19 vaccine was found to be both safe and about 93% effective in preventing infection among study volunteers, all age 18 or older.

Based on the comparison between people who got COVID-19 in the placebo group, the Moderna COVID-19 vaccine was 98% effective at preventing serious COVID-19 illness. Vaccine effect was predicted for younger people based on that clinical trial data as well.

The vaccine is approved under the name Spikevax for people age 12 and older. The vaccine is authorized for use in people age 6 months to 11 years. The number of shots needed varies based on a person's age and COVID-19 vaccination history.

• 2023-2024 Novavax COVID-19 vaccine, adjuvanted. This vaccine is available under an emergency use authorization for people age 12 and older. It requires two shots, given 3 to 8 weeks apart. Research done before the spread of the delta and omicron variants has shown that the vaccine is 90% effective at preventing mild, moderate and severe disease with COVID-19 . For people age 65 and older, the vaccine is 79% effective.

How do the COVID-19 vaccines work?

Both the Pfizer-BioNTech and the Moderna COVID-19 vaccines use genetically engineered messenger RNA (mRNA). Coronaviruses have a spikelike structure on their surface called an S protein. COVID-19 mRNA vaccines give your cells instructions for how to make a harmless piece of an S protein.

After vaccination, your muscle cells begin making the S protein pieces and displaying them on cell surfaces. The immune system recognizes the protein and begins building an immune response and making antibodies. After delivering instructions, the mRNA is immediately broken down. It never enters the nucleus of your cells, where your DNA is kept.

The Novavax COVID-19 , adjuvanted vaccine is a protein subunit vaccine. These vaccines include only the parts (proteins) of a virus that best stimulate your immune system. The Novavax COVID-19 vaccine contains harmless S proteins. It also has an ingredient called an adjuvant that helps with your immune system response.

Once your immune system recognizes the S proteins, this vaccine creates antibodies and defensive white blood cells. If you later become infected with the COVID-19 virus, the antibodies will fight the virus.

Protein subunit COVID-19 vaccines don't use any live virus and can't cause you to become infected with the COVID-19 virus. The protein pieces also don't enter the nucleus of your cells, where your DNA is kept.

Can a COVID-19 vaccine give you COVID-19?

No. The COVID-19 vaccines currently being developed and used in the U.S. don't use the live virus that causes COVID-19 . Because of this, the COVID-19 vaccines can't cause you to become sick with COVID-19 or shed any vaccine parts.

It can take a few weeks for your body to build immunity after getting a COVID-19 vaccination. As a result, it's possible that you could become infected with the virus that causes COVID-19 just before or after being vaccinated.

What are the possible general side effects of a COVID-19 vaccine?

Many people have no side effects from the COVID-19 vaccine. For those who get them, most side effects go away in a few days. A COVID-19 vaccine can cause mild side effects after the first or second dose, including:

• Pain, redness or swelling where the shot was given.
• Muscle pain.
• Joint pain.
• Nausea and vomiting.
• Feeling unwell.
• Swollen lymph nodes.

Babies ages 6 months through 3 years old also might cry, feel sleepy or lose their appetite after vaccination. Children in this age group also may have the common side effects seen in adults. These include pain, redness or swelling where the shot was given, fever, or swollen lymph nodes.

A healthcare team watches you for 15 minutes after getting a COVID-19 vaccine to see if you have an allergic reaction.

If the redness or tenderness where the shot was given gets worse after 24 hours or you're worried about any side effects, contact your healthcare professional.

Are there any long-term side effects of the COVID-19 vaccines?

The vaccines that help protect against COVID-19 are safe and effective. The vaccines were tested in clinical trials. People continue to be watched for rare side effects, even after more than 650 million doses have been given in the United States.

Side effects that don't go away after a few days are thought of as long term. Vaccines rarely cause any long-term side effects.

If you're concerned about side effects, safety data on COVID-19 vaccines is reported to a national program called the Vaccine Adverse Event Reporting System in the U.S. This data is available to the public. The CDC also has created v-safe, a smartphone-based tool that allows users to report COVID-19 vaccine side effects.

If you have other questions or concerns about your symptoms, talk to your healthcare professional.

Can COVID-19 vaccines affect the heart?

In some people, COVID-19 vaccines can lead to heart complications called myocarditis and pericarditis. Myocarditis is the swelling, also called inflammation, of the heart muscle. Pericarditis is the swelling, also called inflammation, of the lining outside the heart.

The risk of myocarditis or pericarditis after a COVID-19 vaccine is rare. These conditions have been reported after a COVID-19 vaccination with any of the three available vaccines. Most cases have been reported in males ages 12 to 39.

If you or your child develops myocarditis or pericarditis after getting a COVID-19 vaccine, talk to a healthcare professional before getting another dose of the vaccine.

Of the cases reported, the problem happened more often after the second dose of the COVID-19 vaccine and typically within one week of COVID-19 vaccination. Most of the people who got care felt better after receiving medicine and resting.

Symptoms to watch for include:

• Chest pain.
• Shortness of breath.
• Feelings of having a fast-beating, fluttering or pounding heart.

If you or your child has any of these symptoms within a week of getting a COVID-19 vaccine, seek medical care.

Things to know before a COVID-19 vaccine

Are covid-19 vaccines free.

In the U.S., COVID-19 vaccines may be offered at no cost through insurance coverage. For people whose vaccines aren't covered or for those who don't have health insurance, options are available. Anyone younger than 18 years old can get no-cost vaccines through the Vaccines for Children program. Adults can get no-cost COVID-19 vaccines through the temporary Bridges to Access program, which is scheduled to end in December 2024.

Can I get a COVID-19 vaccine if I have an existing health condition?

Yes, COVID-19 vaccines are safe for people who have existing health conditions, including conditions that have a higher risk of getting serious illness with COVID-19 .

Your healthcare team may suggest you get added doses of a COVID-19 vaccine if you have a moderately or severely weakened immune system. Talk to your healthcare team if you have any questions about when to get a COVID-19 vaccine.

Is it OK to take an over-the-counter pain medicine before or after getting a COVID-19 vaccine?

Don't take medicine before getting a COVID-19 vaccine to prevent possible discomfort. It's not clear how these medicines might impact the effectiveness of the vaccines. However, it's OK to take this kind of medicine after getting a COVID-19 vaccine, as long as you have no other medical reason that would prevent you from taking it.

Allergic reactions and COVID-19 vaccines

What are the signs of an allergic reaction to a covid-19 vaccine.

You might be having an immediate allergic reaction to a COVID-19 vaccine if you experience these symptoms within four hours of getting vaccinated:

• Swelling of the lips, eyes or tongue.

If you have any signs of an allergic reaction, get help right away. Tell your healthcare professional about your reaction, even if it went away on its own or you didn't get emergency care. This reaction might mean you are allergic to the vaccine. You might not be able to get a second dose of the same vaccine. However, you might be able to get a different vaccine for your second dose.

Can I get a COVID-19 vaccine if I have a history of allergic reactions?

If you have a history of severe allergic reactions not related to vaccines or injectable medicines, you may still get a COVID-19 vaccine. You're typically monitored for 30 minutes after getting the vaccine.

If you've had an immediate allergic reaction to other vaccines or injectable medicines, ask your healthcare professional about getting a COVID-19 vaccine. If you've ever had an immediate or severe allergic reaction to any ingredient in a COVID-19 vaccine, the CDC recommends not getting that specific vaccine.

If you have an immediate or severe allergic reaction after getting the first dose of a COVID-19 vaccine, don't get the second dose. But you might be able to get a different vaccine for your second dose.

Pregnancy, breastfeeding and fertility with COVID-19 vaccines

Can pregnant or breastfeeding women get the covid-19 vaccine.

If you are pregnant or breastfeeding, the CDC recommends that you get a COVID-19 vaccine. Getting a COVID-19 vaccine can protect you from severe illness due to COVID-19 . Vaccination also can help pregnant women build antibodies that might protect their babies.

COVID-19 vaccines don't cause infection with the virus that causes COVID-19 , including in pregnant women or their babies. None of the COVID-19 vaccines contains the live virus that causes COVID-19 .

Children and COVID-19 vaccines

If children don't often experience severe illness with covid-19, why do they need a covid-19 vaccine.

While rare, some children can become seriously ill with COVID-19 after getting the virus that causes COVID-19 .

A COVID-19 vaccine might prevent your child from getting the virus that causes COVID-19 . It also may prevent your child from becoming seriously ill or having to stay in the hospital due to the COVID-19 virus.

After a COVID-19 vaccine

Can i stop taking safety precautions after getting a covid-19 vaccine.

You are considered up to date with your vaccines if you have gotten all recommended COVID-19 vaccine shots when you become eligible.

After getting vaccinated, you can more safely return to doing activities that you might not have been able to do because of high numbers of people with COVID-19 in your area. However, if you're in an area with a high number of people with COVID-19 in the hospital, the CDC recommends wearing a well-fitted mask indoors in public, whether or not you're vaccinated.

If you have a weakened immune system or have a higher risk of serious illness, wear a mask that provides you with the most protection possible when you're in an area with a high number of people with COVID-19 in the hospital. Check with your healthcare professional to see if you should wear a mask at other times.

The CDC recommends that you wear a mask on planes, buses, trains and other public transportation traveling to, within or out of the U.S., as well as in places such as airports and train stations.

If you've gotten all recommended vaccine doses and you've had close contact with someone who has the COVID-19 virus, get tested at least five days after the contact happens.

Can I still get COVID-19 after I'm vaccinated?

COVID-19 vaccination will protect most people from getting sick with COVID-19 . But some people who are up to date with their vaccines may still get COVID-19 . These are called vaccine breakthrough infections.

People with vaccine breakthrough infections can spread COVID-19 to others. However, people who are up to date with their vaccines but who have a breakthrough infection are less likely to have serious illness with COVID-19 than those who are not vaccinated. Even when people who are vaccinated develop symptoms, they tend to be less severe than those experienced by unvaccinated people.

Are the new COVID-19 vaccines safe?

Andrew Badley, M.D., COVID-19 Research Task Force Chair, Mayo Clinic: The safety of these vaccines has been studied extensively. They've been tested now in about 75,000 patients in total, and the incidence of adverse effects is very, very low.

These vaccines were fast-tracked, but the parts that were fast-tracked were the paperwork; so the administrative approvals, the time to get the funding — those were all fast-tracked. Because these vaccines have such great interest, the time it took to enroll patients was very, very fast. The follow up was as thorough as it is for any vaccine, and we now have months of data on patients who received the vaccine or placebo, and we've compared the incidence of side effects between patients who received the vaccine and placebo, and that incidence of side effects, other than injection site reaction, is no different.

The side effects to the vaccines are very mild. Some of them are quite common. Those include injection site reactions, fevers, chills, and aches and pains. In a very, very small subset of patients — those patients who've had prior allergic reactions — some patients can experience allergic reaction to the vaccine. Right now we believe that number is exceedingly low.

There is a problem with information submitted for this request. Review/update the information highlighted below and resubmit the form.

From Mayo Clinic to your inbox

Sign up for free and stay up to date on research advancements, health tips, current health topics, and expertise on managing health. Click here for an email preview.

Error Email field is required

Error Include a valid email address

To provide you with the most relevant and helpful information, and understand which information is beneficial, we may combine your email and website usage information with other information we have about you. If you are a Mayo Clinic patient, this could include protected health information. If we combine this information with your protected health information, we will treat all of that information as protected health information and will only use or disclose that information as set forth in our notice of privacy practices. You may opt-out of email communications at any time by clicking on the unsubscribe link in the e-mail.

Thank you for subscribing!

You'll soon start receiving the latest Mayo Clinic health information you requested in your inbox.

Sorry something went wrong with your subscription

Please, try again in a couple of minutes

• Stay up to date with your vaccines. Centers for Disease Control and Prevention. https://www.cdc.gov/coronavirus/2019-ncov/vaccines/stay-up-to-date.html. Accessed Oct. 6, 2023.
• AskMayoExpert. COVID-19: Vaccination. Mayo Clinic; 2022.
• Selected adverse events reported after COVID-19 vaccination. Centers for Disease Control and Prevention. https://www.cdc.gov/coronavirus/2019-ncov/vaccines/safety/adverse-events.html. Accessed Jan. 19, 2022.
• COVID-19 vaccines for people with allergies. Centers for Disease Control and Prevention. https://www.cdc.gov/coronavirus/2019-ncov/vaccines/recommendations/specific-groups/allergies.html. Accessed Jan. 19, 2022.
• Possible side effects after getting a COVID-19 vaccine. Centers for Disease Control and Prevention. https://www.cdc.gov/coronavirus/2019-ncov/vaccines/expect/after.html. Accessed Jan. 19, 2022.
• How to protect yourself & others. Centers for Disease Control and Prevention. https://www.cdc.gov/coronavirus/2019-ncov/prevent-getting-sick/prevention.html. Jan. 18, 2022.
• Quarantine and isolation. Centers for Disease Control and Prevention. https://www.cdc.gov/coronavirus/2019-ncov/your-health/quarantine-isolation.html. Accessed Jan. 19, 2022.
• Understanding mRNA COVID-19 vaccines. Centers for Disease Control and Prevention. https://www.cdc.gov/coronavirus/2019-ncov/vaccines/different-vaccines/mrna.html. Accessed Jan. 19, 2022.
• Frequently asked questions about COVID-19 vaccination. Centers for Disease Control and Prevention. https://www.cdc.gov/coronavirus/2019-ncov/vaccines/faq.html. Accessed Jan. 19, 2022.
• Domestic travel during COVID-19. Centers for Disease Control and Prevention. https://www.cdc.gov/coronavirus/2019-ncov/travelers/travel-during-covid19.html. Accessed Jan. 20, 2022.
• COVID-19 vaccine booster shots. Centers for Disease Control and Prevention. https://www.cdc.gov/coronavirus/2019-ncov/vaccines/booster-shot.html. Accessed Sept. 8, 2022.
• Requirement for proof of negative COVID-19 test or documentation of recovery from COVID-19. Centers for Disease Control and Prevention. https://www.cdc.gov/coronavirus/2019-ncov/travelers/testing-international-air-travelers.html. Accessed Jan. 19, 2022.
• What you need to know about variants. Centers for Disease Control and Prevention. https://www.cdc.gov/coronavirus/2019-ncov/variants/variant.html. Accessed Feb 16, 2022.
• COVID-19 vaccines while pregnant or breastfeeding. Centers for Disease Control and Prevention. https://www.cdc.gov/coronavirus/2019-ncov/vaccines/recommendations/pregnancy.html. Accessed Jan. 19, 2022.
• Science brief: Omicron (B.1.1.529) variant. Centers for Disease Control and Prevention. https://www.cdc.gov/coronavirus/2019-ncov/science/science-briefs/scientific-brief-omicron-variant.html. Accessed Dec. 3, 2021.
• COVID-19 vaccine booster shots. Centers for Disease Control and Prevention. https://www.cdc.gov/coronavirus/2019-ncov/vaccines/booster-shot.html. Accessed Nov. 30, 2021.
• Coronavirus (COVID-19) update: FDA authorizes Pfizer-BioNTech COVID-19 vaccine for emergency use in adolescents in another important action against pandemic. U.S. Food and Drug Administration. https://www.fda.gov/news-events/press-announcements/coronavirus-covid-19-update-fda-authorizes-pfizer-biontech-covid-19-vaccine-emergency-use. Accessed Jan. 20, 2022.
• Comirnaty and Pfizer-BioNTech COVID-19 vaccine frequently asked questions. U.S. Food and Drug Administration. https://www.fda.gov/emergency-preparedness-and-response/mcm-legal-regulatory-and-policy-framework/comirnaty-and-pfizer-biontech-covid-19-vaccine-frequently-asked-questions. Accessed Jan. 20, 2022.
• Science brief: SARS-CoV-2 infection-induced and vaccine-induced immunity. Centers for Disease Control and Prevention. https://www.cdc.gov/coronavirus/2019-ncov/science/science-briefs/vaccine-induced-immunity.html. Accessed Nov. 3, 2021.
• COVID-19 vaccines for people who are moderately or severely immunocompromised. Centers for Disease Control and Prevention. https://www.cdc.gov/coronavirus/2019-ncov/vaccines/recommendations/immuno.html. Accessed Dec. 12, 2022.
• FDA authorizes Pfizer-BioNTech COVID-19 vaccine for emergency use in children 5 through 11 years of age. U.S. Food and Drug Administration. https://www.fda.gov/news-events/press-announcements/fda-authorizes-pfizer-biontech-covid-19-vaccine-emergency-use-children-5-through-11-years-age. Accessed Jan. 20, 2022.
• Delta variant: What we know about the science. Centers for Disease Control and Prevention. https://www.cdc.gov/coronavirus/2019-ncov/variants/delta-variant.html. Accessed Oct. 1, 2021.
• What to do if you had an allergic reaction after getting a COVID-19 vaccine. Centers for Disease Control and Prevention. https://www.cdc.gov/coronavirus/2019-ncov/vaccines/safety/allergic-reaction.html. Accessed Jan. 19, 2022.
• Lipkind HS, et al. Receipt of COVID-19 vaccine during pregnancy and preterm or small-for-gestational-age at birth — Eight integrated health care organizations, United States, December 15, 2020-July 22, 2021. Morbidity and Mortality Weekly Report. 2022; doi:10.15585/mmwr.mm7101e1.
• COVID-19 vaccines for children and teens. Centers for Disease Control and Prevention. https://www.cdc.gov/coronavirus/2019-ncov/vaccines/recommendations/adolescents.html. Accessed Jan. 19, 2022.
• Understanding viral vector COVID-19 vaccines. Centers for Disease Control and Prevention. https://www.cdc.gov/coronavirus/2019-ncov/vaccines/different-vaccines/viralvector.html. Accessed Jan. 19, 2022.
• Vaccine adverse event reporting system (VAERS). Vaccine Adverse Event Reporting System. https://vaers.hhs.gov/. Accessed Jan. 21, 2022.
• V-safe after vaccination health checker. Centers for Disease Control and Prevention. https://www.cdc.gov/coronavirus/2019-ncov/vaccines/safety/vsafe/printresources.html. Accessed Jan. 19, 2022.
• COVID-19 vaccines for persons with underlying medical conditions. Centers for Disease Control and Prevention. https://www.cdc.gov/coronavirus/2019-ncov/vaccines/recommendations/underlying-conditions.html. Accessed Jan. 19, 2022.
• Interim clinical considerations for use of COVID-19 vaccines currently approved or authorized in the United States. Centers for Disease Control and Prevention. https://www.cdc.gov/vaccines/covid-19/clinical-considerations/covid-19-vaccines-us.html. Accessed Oct. 6, 2023.
• Pfizer-BioNTech vaccine: Fact sheet for recipients and caregivers. U.S. Food and Drug Administration. https://www.fda.gov/emergency-preparedness-and-response/coronavirus-disease-2019-covid-19/pfizer-biontech-covid-19-vaccine. Accessed Jan. 20, 2022.
• Myths and facts about COVID-19 vaccines. Centers for Disease Control and Prevention. https://www.cdc.gov/coronavirus/2019-ncov/vaccines/facts.html. Accessed Jan. 19, 2022.
• Janssen COVID-19 vaccine: Fact sheet for recipients and caregivers. U.S. Food and Drug Administration. https://www.fda.gov/emergency-preparedness-and-response/mcm-legal-regulatory-and-policy-framework/emergency-use-authorization#vaccines. Accessed May 9, 2022.
• Health Education & Content Services (Patient Education). COVID-19 vaccine reactions: The difference between common and allergic reactions. Mayo Clinic; 2021.
• The possibility of COVID-19 after vaccination: Breakthrough infections. Centers for Disease Control and Prevention. https://www.cdc.gov/coronavirus/2019-ncov/vaccines/effectiveness/why-measure-effectiveness/breakthrough-cases.html. Accessed Jan. 19, 2022.
• Wang Z, et al. Naturally enhanced neutralizing breadth against SARS-CoV-2 one year after infection. Nature. 2021; doi.org/10.1038/s41586-021-03696-9.
• Myocarditis and pericarditis following mRNA COVID-19 vaccination. Centers for Disease Control and Prevention. https://www.cdc.gov/coronavirus/2019-ncov/vaccines/safety/myocarditis.html. Accessed Jan. 20, 2022.
• Key things to know about COVID-19 vaccines. Centers for Disease Control and Prevention. https://www.cdc.gov/coronavirus/2019-ncov/vaccines/keythingstoknow.html. Accessed Jan. 19, 2022.
• Moderna COVID-19 vaccine: Fact sheet for recipients and caregivers. U.S. Food and Drug Administration. https://www.fda.gov/emergency-preparedness-and-response/coronavirus-disease-2019-covid-19/moderna-covid-19-vaccine#additional. Accessed Jan. 21, 2022.
• Edelman A, et al. Association between menstrual cycle length and coronavirus disease 2019 (COVID-19) vaccination: A U.S. cohort. Obstetrics & Gynecology. 2022; doi:10.1097/AOG.0000000000004695.
• Pregnant and recently pregnant people. Centers for Disease Control and Prevention. https://www.cdc.gov/coronavirus/2019-ncov/need-extra-precautions/pregnant-people.html. Accessed Feb. 28, 2022.
• Halasa NB, et al. Effectiveness of maternal vaccination with mRNA COVID-19 vaccine during pregnancy against COVID-19-associated hospitalization in infants aged < 6 months — 17 states, July 2021-January 2022. MMWR Morbidity and Mortality Weekly Report. 2022; doi:10.15585/mmwr.mm7107e3.
• Use and care of masks. Centers for Disease Control and Prevention. https://www.cdc.gov/coronavirus/2019-ncov/prevent-getting-sick/about-face-coverings.html. Accessed Feb. 28, 2022.
• Statement on Omicron sublineage BA.2. World Health Organization. https://www.who.int/news/item/22-02-2022-statement-on-omicron-sublineage-ba.2. Accessed March 25, 2022.
• Neutralization of the SARS-CoV-2 omicron BA.1 and BA.2 variants. The New England Journal of Medicine. 2022; doi:10.1056/NEJMc2201849.
• COVID data tracker: Variant proportions. Centers for Disease Control and Prevention. https://covid.cdc.gov/covid-data-tracker/#variant-proportions. Accessed April 13, 2023.
• Coronavirus (COVID-19) update: FDA authorizes second booster dose of two COVID-19 vaccines for older and immunocompromised individuals. U.S. Food and Drug Administration. https://www.fda.gov/news-events/press-announcements/coronavirus-covid-19-update-fda-authorizes-second-booster-dose-two-covid-19-vaccines-older-and. Accessed March 30, 2022.
• Coronavirus (COVID-19) update: FDA limits use of Janssen COVID-19 vaccine to certain individuals. U.S. Food and Drug Administration. https://www.fda.gov/news-events/press-announcements/coronavirus-covid-19-update-fda-limits-use-janssen-covid-19-vaccine-certain-individuals. Accessed May 9, 2022.
• Coronavirus (COVID-19) update: FDA expands eligibility for Pfizer-BioNTech COVID-19 vaccine booster dose to children 5 through 11 years. U.S. Food and Drug Administration. https://www.fda.gov/news-events/press-announcements/coronavirus-covid-19-update-fda-expands-eligibility-pfizer-biontech-covid-19-vaccine-booster-dose. Accessed May 18, 2022.
• COVID-19 vaccine boosters. Centers for Disease Control and Prevention. https://www.cdc.gov/coronavirus/2019-ncov/vaccines/booster-shot.html. Accessed May 23, 2022.
• Coronavirus (COVID-19) update: FDA authorizes Moderna and Pfizer-BioNTech COVID-19 vaccines for children down to 6 months of age. Centers for Disease Control and Prevention. https://www.fda.gov/news-events/press-announcements/coronavirus-covid-19-update-fda-authorizes-moderna-and-pfizer-biontech-covid-19-vaccines-children. Accessed June 21, 2022.
• Fact sheet for healthcare providers administering vaccine. U.S. Food and Drug Administration. https://www.fda.gov/emergency-preparedness-and-response/coronavirus-disease-2019-covid-19/comirnaty-and-pfizer-biontech-covid-19-vaccine. Accessed June 20, 2022.
• Masking during travel. Centers for Disease Control and Prevention. https://wwwnc.cdc.gov/travel/page/masks. Accessed Oct. 6, 2023.
• SARS-CoV-2 variant classifications and definitions. Centers for Disease Control and Prevention. https://www.cdc.gov/coronavirus/2019-ncov/variants/variant-classifications.html. Accessed April 13, 2023.
• FDA roundup. U.S. Food and Drug Administration. https://www.fda.gov/news-events/press-announcements/fda-roundup-july-8-2022. Accessed July 15, 2022.
• Coronavirus (COVID-19) update: FDA authorizes emergency use of Novavax COVID-19 vaccine, adjuvanted. U.S. Food and Drug Administration. https://www.fda.gov/news-events/press-announcements/coronavirus-covid-19-update-fda-authorizes-emergency-use-novavax-covid-19-vaccine-adjuvanted. Accessed July 15, 2022.
• Novavax COVID-19, adjuvanted vaccine: Overview and safety. Centers for Disease Control and Prevention. https://www.cdc.gov/coronavirus/2019-ncov/vaccines/novavax.html. Accessed July 20, 2022.
• Understanding protein subunit COVID-19 vaccines. Centers for Disease Control and Prevention. https://www.cdc.gov/coronavirus/2019-ncov/vaccines/different-vaccines/proteinsubunit.html. Accessed July 20, 2022.
• Lee KMN, et al. Investigating trends in those who experience menstrual bleeding changes after SARS-CoV-2 vaccination. Science Advances. doi:10.1126/sciadv.abm720.
• Reinfections and COVID-19. Centers for Disease Control and Prevention. https://www.cdc.gov/coronavirus/2019-ncov/your-health/reinfection.html. Accessed July 21, 2022.
• Novavax COVID-19 vaccine, adjuvanted. Food and Drug Administration. https://www.fda.gov/emergency-preparedness-and-response/coronavirus-disease-2019-covid-19/novavax-covid-19-vaccine-adjuvanted. Accessed Oct. 5, 2023.
• Variants and genomic surveillance. Centers for Disease Control and Prevention. https://covid.cdc.gov/covid-data-tracker/#variant-proportions. Accessed Aug. 23, 2022.
• COVID-19 bivalent vaccine boosters. U.S. Food and Drug Administration. https://www.fda.gov/emergency-preparedness-and-response/coronavirus-disease-2019-covid-19/covid-19-bivalent-vaccine-boosters. Accessed Sept. 9, 2022.
• Pediatric data. Centers for Disease Control and Prevention. https://covid.cdc.gov/covid-data-tracker/#pediatric-data. Accessed March 21, 2023.
• Benefits of getting a COVID-19 vaccine. Centers for Disease Control and Prevention. https://www.cdc.gov/coronavirus/2019-ncov/vaccines/vaccine-benefits.html. Accessed Oct. 22, 2023.
• Plumb ID, et al. Effectiveness of COVID-19 mRNA vaccination in preventing COVID-19-associated hospitalization among adults with previous SARS-CoV-2 infection. MMWR Morbidity and Mortality Weekly Report. 2022; doi.org/10.15585/mmwr.mm7115e2.
• Vaccine effectiveness studies. Centers for Disease Control and Prevention. https://www.cdc.gov/coronavirus/2019-ncov/vaccines/effectiveness/how-they-work.html. Accessed Oct. 22, 2023.
• Comirnaty. U.S. Food and Drug Administration. https://www.fda.gov/vaccines-blood-biologics/Comirnaty. Accessed June 19, 2023.
• Spikevax summary basis for regulatory action. U.S. Food and Drug Administration. https://www.fda.gov/vaccines-blood-biologics/Spikevax. Accessed June 19, 2023.
• Spikevax package insert. U.S. Food and Drug Administration. https://www.fda.gov/vaccines-blood-biologics/Spikevax. Accessed June 19, 2023.
• Overview of COVID-19 Vaccines. Centers for Disease Control and Prevention. https://www.cdc.gov/coronavirus/2019-ncov/vaccines/different-vaccines/overview-COVID-19-vaccines.html. Accessed June 19, 2023.
• Pfizer-BioNTech emergency use authorization for unapproved product review memorandum. U.S. Food and Drug Administration. https://www.fda.gov/vaccines-blood-biologics/Comirnaty. Accessed June 19, 2023.
• Link-Gelles, et al. Estimates of bivalent mRNA vaccine durability in preventing COVID-19-associated hospitalization and critical illness among adults with and without immunocompromising conditions — VISION network, September 2022-April 2023. MMWR Morbidity and Mortality Weekly Report. 2023; doi:10.15585/mmwr.mm7221a3.
• Updated COVID-19 vaccines for use in the United States beginning in fall 2023. U.S. Food and Drug Administration. https://www.fda.gov/vaccines-blood-biologics/updated-covid-19-vaccines-use-united-states-beginning-fall-2023. Accessed Oct. 4, 2023.
• Coronavirus (COVID-19), CBER-regulated biologics: COVID-19 vaccines. U.S. Food and Drug Administration. https://www.fda.gov/vaccines-blood-biologics/industry-biologics/coronavirus-covid-19-cber-regulated-biologics. Accessed Oct. 4, 2023.
• Vaccines for children. Centers for Disease Control and Prevention. https://www.cdc.gov/vaccines/programs/vfc/index.html. Accessed Oct. 5, 2023.
• Bridge access program. Centers for Disease Control and Prevention. https://www.cdc.gov/vaccines/programs/bridge/index.html. Accessed Oct. 5, 2023.
• When getting your vaccine. Centers for Disease Control and Prevention. https://www.cdc.gov/coronavirus/2019-ncov/vaccines/expect.html. Accessed Oct. 11, 2023.
• Orenstein W, et al., eds. Vaccine safety. In: Plotkin's Vaccines. 8th ed. Elsevier; 2024. https://www.clinicalkey.com. Accessed April 21, 2023.
• Vaccines, memorandum re: fall 2022 COVID-19 vaccine strain composition selection recommendation. U.S. Food and Drug Administration. https://www.fda.gov/vaccines-blood-biologics/vaccines. Accessed Oct. 11, 2023.
• Deng J, et al. Severity and outcomes of SARS-CoV-2 reinfection compared with primary infection: A systematic review and meta-analysis. International Journal of Environmental Research and Public Health. 2023; doi:10.3390/ijerph20043335.

Products and Services

• A Book: Endemic - A Post-Pandemic Playbook
• Begin Exploring Women's Health Solutions at Mayo Clinic Store
• A Book: Future Care
• Antibiotics: Are you misusing them?
• COVID-19 and vitamin D
• Convalescent plasma therapy
• Coronavirus disease 2019 (COVID-19)
• COVID-19: How can I protect myself?
• Herd immunity and coronavirus
• COVID-19 and pets
• COVID-19 and your mental health
• COVID-19 antibody testing
• COVID-19, cold, allergies and the flu
• COVID-19 drugs: Are there any that work?
• Long-term effects of COVID-19
• COVID-19 tests
• COVID-19 in babies and children
• Coronavirus infection by race
• COVID-19 travel advice
• COVID-19 vaccine: Should I reschedule my mammogram?
• COVID-19 vaccines for kids: What you need to know
• COVID-19 variant
• COVID-19 vs. flu: Similarities and differences
• COVID-19: Who's at higher risk of serious symptoms?
• Debunking coronavirus myths
• Different COVID-19 vaccines
• Extracorporeal membrane oxygenation (ECMO)
• Fever: First aid
• Fever treatment: Quick guide to treating a fever
• Fight coronavirus (COVID-19) transmission at home
• Honey: An effective cough remedy?
• How do COVID-19 antibody tests differ from diagnostic tests?
• How to take your pulse
• How to measure your respiratory rate
• How to take your temperature
• How well do face masks protect against COVID-19?
• Is hydroxychloroquine a treatment for COVID-19?
• Loss of smell
• Mayo Clinic Minute: You're washing your hands all wrong
• Mayo Clinic Minute: How dirty are common surfaces?
• Multisystem inflammatory syndrome in children (MIS-C)
• Nausea and vomiting
• Pregnancy and COVID-19
• Safe outdoor activities during the COVID-19 pandemic
• Safety tips for attending school during COVID-19
• Sex and COVID-19
• Shortness of breath
• Thermometers: Understand the options
• Treating COVID-19 at home
• Unusual symptoms of coronavirus
• Vaccine guidance from Mayo Clinic
• Watery eyes

Related information

• Debunking COVID-19 myths - Related information Debunking COVID-19 myths
• Different types of COVID-19 vaccines: How they work - Related information Different types of COVID-19 vaccines: How they work
• COVID-19 vaccines for kids: What you need to know - Related information COVID-19 vaccines for kids: What you need to know
• COVID-19 vaccines Get the facts

Your gift holds great power – donate today!

Make your tax-deductible gift and be a part of the cutting-edge research and care that's changing medicine.

Cardiovascular risks and COVID-19 : New research confirms the benefits of vaccination

Member, IMPART (Initiative on Medication Management, Policy Analysis, Research & Training), Dalhousie University

Disclosure statement

Glen Pyle receives funding from the Heart and Stroke Foundation of Canada, Canadian Institutes of Health Research, and the Natural Sciences and Engineering Research Council of Canada. He is a on the advisory board of "Royal City Science" and "Science Up First".

Dalhousie University provides funding as a founding partner of The Conversation CA.

Dalhousie University provides funding as a member of The Conversation CA-FR.

View all partners

COVID-19 is a respiratory disease. Yet, from the earliest days of the pandemic, the cardiovascular risks associated with SARS-CoV-2 infection were clear: individuals with severe cases of COVID-19 often died from cardiovascular complications, and those with pre-existing cardiovascular disease were more likely to have severe illness or die.

In short, the cardiovascular system has played a central role in COVID-19 since the beginning.

It is not surprising that as debate over COVID-19 and vaccines flared that cardiovascular disease was a central issue . Those opposed to vaccination often make claims of cardiovascular risks that exceed any benefits. But when data on COVID-19, vaccines and cardiovascular health are reviewed, the conclusions are clear: vaccines are safe and effective at reducing the cardiovascular complications that are a hallmark of COVID-19.

Hot off the presses

A new study of 20.5 million people in the United Kingdom, Spain and Estonia used electronic health records to determine how COVID-19 vaccines affect cardiovascular complications following SARS-CoV-2 infection. Roughly the same number of vaccinated and unvaccinated subjects were included, and the vaccinated group consisted of people who received at least one of the AstraZeneca, Pfizer, Moderna or Janssen vaccines.

The study found that common cardiovascular complications of COVID-19 — including blood clots, stroke, arrhythmias and heart attacks — were substantially reduced in the vaccinated group, with protective effects lasting up to a year after vaccination.

Bigger picture

While this most recent study represents one of the most comprehensive investigations into the cardiovascular benefits of COVID-19 vaccination, its findings are consistent with earlier, smaller studies.

A 2022 study of 231,037 people found two doses of COVID-19 vaccines reduced the risk of stroke and heart attack up to four months after a breakthrough infection.

A subsequent study of 1.9 million people found that while two doses of the mRNA vaccines or one dose of the Johnson & Johnson vaccine protected against major cardiovascular events following COVID-19, even a single dose of the mRNA vaccines offered some benefit in reducing the risk of cardiovascular complications.

Health-care decisions require a weighing of the risk and benefits of treatments, and for COVID-19 vaccines the low cardiovascular risks favour vaccination. A study of over four million vaccinated Australians found no increase in sudden cardiac death. Even patients with pre-existing heart failure do not have an increased risk of worsening heart failure, myocarditis, or blood clots following vaccination.

Weighing the risks

Although the safety of COVID-19 vaccines is well-established, it does not mean there are no risks. A review of 99 million individuals in the Global Vaccine Data Network confirmed earlier studies that found an increased risk of myocarditis and pericarditis, which is seen primarily in young males — historically the group most at risk for myocarditis before COVID-19 emerged.

While individuals at higher risk for these complications should consult with their health-care providers in making decisions about vaccination, it should be noted that the risk for myocarditis and pericarditis is generally higher with COVID-19, even in this cohort.

Read more: Myocarditis: COVID-19 is a much bigger risk to the heart than vaccination

Studies have also found that extending the time between first and second doses of the COVID-19 mRNA vaccines beyond the initially recommended three-week interval decreases the risk of myocarditis . Furthermore, post-vaccine myocarditis tends to be transient with very good recovery and is less severe than that associated with COVID-19.

The risk of myocarditis in young people has led some to claim that the benefits of COVID-19 vaccines are negated when stacked up against the chance of heart inflammation. A statement from the American Heart Association confirms that the risks of cardiovascular complications in young people with more mild cases of COVID-19 (symptoms lasting less than four days) are low, but notes that there are concerning signs for those who experience more severe illness with infection.

Furthermore, other cardiovascular risks associated with infection must be considered in weighing risks and benefits. These include multisystem inflammatory syndrome or “MIS-C” and cardiac arrhythmias — a far more common risk of COVID-19 than myocarditis.

Finally, the claim that COVID-19 is harmless in children is not true: in Canada COVID-19 is the sixth leading cause of death for children aged one to 14 years, and tenth for people 15 to 19 years old. Overall, studies find that even in young people the benefits of vaccination exceed the risks , particularly when it comes to cardiovascular disease.

Take to heart

There are individuals whose health conditions preclude COVID-19 vaccination , and others for whom health risks may outweigh the benefits. But, for the vast majority of people — including young and otherwise healthy people — COVID-19 vaccination is not only safe, but the cardiovascular protection it offers could be life-saving.

• Cardiovascular disease
• Heart health
• Myocarditis
• COVID-19 vaccines
• AstraZeneca
• Covid vaccination
• COVID-19 vaccine hesitancy

Events Officer

Lecturer (Hindi-Urdu)

Director, Defence and Security

Opportunities with the new CIEHF

School of Social Sciences – Public Policy and International Relations opportunities

• Type 2 Diabetes
• Heart Disease
• Digestive Health
• Multiple Sclerosis
• COVID-19 Vaccines
• Occupational Therapy
• Healthy Aging
• Health Insurance
• Public Health
• Patient Rights
• Caregivers & Loved Ones
• End of Life Concerns
• Health News
• Thyroid Test Analyzer
• Doctor Discussion Guides
• Hemoglobin A1c Test Analyzer
• Lipid Test Analyzer
• Complete Blood Count (CBC) Analyzer
• What to Buy
• Editorial Process
• Meet Our Medical Expert Board

New Research Supports an Annual COVID Vaccine Plan

Photo Illustration by Amelia Manley for Verywell Health; Getty Images

Key Takeaways

• New research suggests that most people will benefit from an annual COVID-19 vaccine.
• Certain groups may need two vaccines a year.
• Doctors said more needs to be done to encourage people to get vaccinated.

There have been a lot of changes in recommendations around COVID-19 vaccines over the past few years, making it difficult to know whether you need another shot and how often you should get one. Now, new research from the Yale School of Public Health has recommendations for a vaccine cadence moving forward.

The study, which was published in the Annals of Internal Medicine , used computer simulations to compare five annual vaccination strategies and predict outcomes. The researchers discovered that getting an annual COVID vaccine with a second dose for adults over 50 and children under 2 was linked to fewer hospitalizations, fewer deaths, and less healthcare spending each year.

This isn’t revolutionary: The Centers for Disease Control and Prevention (CDC) already proposed similar interim guidelines, although they’re slightly different. But it backs up existing recommendations around COVID vaccines.

Is an Annual COVID Shot Realistic?

While the COVID vaccine was relatively popular when it first rolled out, many people haven’t gotten the most recent 2023-2024 updated version . Current data show that less than 23% of the adult population in the U.S. has gotten the updated vaccine. The numbers are even lower in children; less than 14% of children aged 6 months to 17 years have received the updated vaccine.  

Current recommendations from the CDC say that people 65 and up should receive an additional dose of the COVID-19 vaccine, but the new Yale study suggests it would be more effective if people did this starting at age 50.

Given how few people have gotten the updated vaccine to begin with, do doctors actually think the public will embrace this?

“This sounds familiar and it rather mirrors what, by and large, is happening to date,” William Schaffner, MD , an infectious disease specialist and professor at the Vanderbilt University School of Medicine, told Verywell. While older people have been the most likely to follow recommendations around COVID vaccines, Schaffner said it’s been tricky to get parents on board.

“The vast majority of parents have not taken their child in to be vaccinated with even their first dose,” he said. “Pediatricians are going to have to do a lot of friendly persuasion to get that group vaccinated. Parents just do not see the current Omicron variants distinctly impacting children.”

If a new concerning COVID-19 variant emerges, though, recommendations could change, Schaffner said.

What About People Who Are Immunocompromised?

The study didn’t address the ideal vaccine cadence for people who are immunocompromised. If you have a condition that causes you to be immunocompromised, it’s important to consult your doctor, said infectious disease expert  Amesh A. Adalja, MD , senior scholar at the Johns Hopkins Center for Health Security.

“Immunocompromised individuals may have to have individualized vaccination schedules dependent upon their net state of immunosuppression,” Adalja told Verywell. He noted that the word ‘immunosuppression’ is used very generally, “but it is a phenomenon that has degrees.”

The CDC has COVID vaccine recommendations for immunocompromised people, but it’s very specific to age, type of vaccine, and current level of vaccination.

“The standing recommendation is that these individuals can get repeated doses if they are moderately or severely immunocompromised and at least two months have passed since their last dose,” Schaffner said.

How Doctors Can Increase Vaccination Rates

Doctors suggest coupling your COVID vaccine with your flu shot. The convenience of a combined appointment increases the odds people will get both vaccines.

“The annual rate of people getting the flu shot is about 50% of the population, but that’s better than it is for the COVID vaccine,” Timothy Murphy, MD, senior associate dean for clinical and translational research at the University at Buffalo Jacobs School of Medicine and Biomedical Sciences, told Verywell. “Pairing the COVID vaccine with the flu vaccine might increase the likelihood of people getting it.”

Schaffner agrees.

“We have to promote this as a circumstance where in the fall, you roll up both your sleeves,” he said. While it’s not available yet, a combination flu and COVID-19 vaccine would likely increase use of both vaccines even more. “It would also make life easier,” Schaffner said.

What This Means For You

COVID-19 vaccine can lower your risk of being hospitalized and dying from the virus, so you should make sure you have the latest shot available every year. If you’re unsure what your personal needs are regarding the vaccine, consult with your primary care physician for more information.

The information in this article is current as of the date listed, which means newer information may be available when you read this. For the most recent updates on COVID-19, visit our  coronavirus news page .

Wells CR, Pandey A, Moghadas SM, Fitzpatrick MC, Singer BH, Galvani AP. Evaluation of strategies for transitioning to annual SARS-CoV-2 vaccination campaigns in the United States . Ann Intern Med . Published online March 26, 2024. doi:10.7326/M23-2451

Centers for Disease Control and Prevention. Interim clinical considerations for use of Covid-19 vaccines in the United States .

Centers for Disease Control and Prevention. COVIDVaxView: adult coverage and intent .

Centers for Disease Control and Prevention. COVIDVaxView: child coverage and parental intent for vaccination .

Centers for Disease Control and Prevention. Interim clinical considerations for use of COVID-19 vaccines in the United States .

By Korin Miller Korin Miller is a health and lifestyle journalist who has been published in The Washington Post, Prevention, SELF, Women's Health, The Bump, and Yahoo, among other outlets.

Read our research on: Abortion | International Conflict | Election 2024

Regions & Countries

How americans view the coronavirus, covid-19 vaccines amid declining levels of concern, continued decline in share of u.s. adults with up-to-date vaccination.

Pew Research Center conducted this study to understand Americans’ views of the coronavirus and COVID-19 vaccines. For this analysis, we surveyed 10,133 U.S. adults from Feb. 7 to 11, 2024.

Everyone who took part in the survey is a member of the Center’s American Trends Panel (ATP), an online survey panel that is recruited through national, random sampling of residential addresses. This way, nearly all U.S. adults have a chance of selection. The survey is weighted to be representative of the U.S. adult population by gender, race, ethnicity, partisan affiliation, education and other categories. Read more about the ATP’s methodology .

Here are the questions used for this report , along with responses, and its methodology .

A new Pew Research Center survey finds that just 20% of Americans view the coronavirus as a major threat to the health of the U.S. population today and only 10% are very concerned they will get it and require hospitalization. This data represents a low ebb of public concern about the virus that reached its height in the summer and fall of 2020, when as many as two-thirds of Americans viewed COVID-19 as a major threat to public health.

Just 28% of U.S. adults say they have received the updated COVID-19 vaccine, which the Centers for Disease Control and Prevention (CDC) recommended last fall to protect against serious illness. This stands in stark contrast to the spring and summer of 2021, when long lines and limited availability characterized the initial rollout of the first COVID-19 vaccines. A majority of U.S. adults (69%) had been fully vaccinated by August 2021.

Underscoring the limited demand for the updated COVID-19 vaccines, a larger share of U.S. adults say they’ve gotten a flu shot in the last six months than the updated coronavirus vaccine (44% vs. 28%). And despite a public health push encouraging adults to get both vaccines at the same time, almost half of those who received a flu shot from a health care provider chose not to get the updated COVID-19 vaccine.

The vast majority of Americans have some level of protection from the coronavirus because of vaccination, prior infection or a combination of the two. This has led to a decline in severe illness from the disease.

Still, the virus continues to circulate widely in the United States , with wastewater data suggesting that cases in the early part of 2024 were among the highest they have been since the first omicron wave in 2022.  

Long COVID ranks among the concerns of public health experts. Long COVID refers to a variety of symptoms such as fatigue and brain fog that last longer than a month after a COVID-19 infection.

The survey – conducted among 10,133 U.S. adults from Feb. 7 to 11, 2024 – finds that 50% of Americans say it is extremely or very important for medical researchers and health care providers to understand and treat long COVID; 27% see this as a less important issue and 22% of Americans say they haven’t heard of long COVID.

Continuity and change: Partisan views of COVID-19

Partisanship remains one of the most powerful factors shaping views about COVID-19 vaccines and the virus. But the size and nature of differences between Republicans and Democrats have evolved since earlier stages of the outbreak.

For instance, the gap between the shares of Democrats and Republicans who view the coronavirus as a major threat to public health has fallen from 37 percentage points in May 2022 to 16 points today. In the pandemic’s first year, Democrats were routinely about 40 points more likely than Republicans to view the coronavirus as a major threat to the health of the U.S. population. This gap has waned as overall levels of concern have fallen.

When it comes to vaccination, Democrats and Democratic-leaning independents remain more likely than Republicans and GOP leaners to say they’ve received an updated COVID-19 vaccine (42% vs. 15%). This 27-point gap in recent vaccination is about the same as in January 2022 when 62% of Democrats and 33% of Republicans said they were up to date (i.e., fully vaccinated and recently boosted).

In addition to partisanship, age continues to matter a great deal in attitudes and behaviors tied to the coronavirus. And the intersection of partisanship and age reveals one of the biggest recent changes in the public’s response to the outbreak: a growing divergence between the oldest Republicans and oldest Democrats in vaccine uptake, which is explored below.

COVID-19 vaccination among adults ages 65 and older, by party

Older adults continue to be one of the most at-risk groups for severe illness and death from COVID-19.

When vaccines first became available in 2021, large majorities of both Republicans and Democrats ages 65 and older said they had received the vaccine. But as additional doses have become available, uptake among older Republicans has declined at a faster rate than among older Democrats.

In the current survey, 66% of Democrats ages 65 and older say they have received the updated COVID-19 vaccine, compared with 24% of Republicans ages 65 and older.

This 42-point partisan gap is much wider now than at other points since the start of the outbreak. For instance, in August 2021, 93% of older Democrats and 78% of older Republicans said they had received all the shots needed to be fully vaccinated (a 15-point gap). Go to the Appendix for more details .

How COVID-19 vaccination varies by age within parties

The impact of age is also striking when looking within political parties.

Among Democrats, about three-in-ten adults under 50 have received an updated COVID-19 vaccine, compared with 48% of those ages 50 to 64 and 66% of Democrats ages 65 and older.

Age differences within the GOP run in the same direction, but are much more modest, reflecting, in part, low overall levels of vaccine uptake.

How COVID-19 vaccination varies by race and ethnicity

Similar shares of White (28%), Black (29%) and Hispanic (27%) adults say they have gotten the updated vaccine. English-speaking Asian adults (35%) are slightly more likely to report receiving the updated vaccine.

As in past Center surveys, there are racial and ethnic differences in vaccine uptake among Democrats.

For instance, 50% of White Democrats and 42% of English-speaking Asian Democrats report having received the updated vaccine, compared with somewhat smaller shares of Black and Hispanic Democrats (32% each).

Views of long COVID

Half of Americans say it is extremely or very important for medical researchers and health care providers to understand and treat long COVID, considering all the different priorities they face.

About two-in-ten (21%) say it’s somewhat important for those in medicine to address long COVID, while 6% say it is not too or not at all important. Another 22% say they haven’t heard of long COVID.

More Democrats (61%) than Republicans (37%) say it is extremely or very important for medical researchers and health care providers to understand and treat long COVID.

A majority of women (56%) consider this extremely or very important; a smaller share of men (44%) say the same. The CDC has reported that women are more likely than men to develop long COVID symptoms.

Awareness of long COVID also shapes views on its importance: Those who have heard a lot about long COVID are more likely than those who have heard a little about it to say it’s extremely or very important for medical professional to address it (76% vs. 60%).

Views of the threat posed by the coronavirus

One-in-five Americans now say the coronavirus is a major threat to the health of the U.S. population, down from a high of 67% in July 2020.

Concern about the coronavirus as a major threat to the U.S. economy has also declined dramatically. Today, 23% of Americans say it’s a major threat to the economy, compared with 88% in May 2020. The pandemic spurred an economic recession in 2020 and a spike in unemployment that reached the highest levels since the Great Recession.

Federal policy on the coronavirus has changed as public concern – and the incidence of severe illness – has fallen. The Biden administration ended the public health emergency for the coronavirus pandemic in May 2023. And the CDC recently released updated guidelines with shorter isolation periods for adults testing positive for the disease.

While large partisan gaps characterized views of the coronavirus as a major threat to public health for much of the pandemic, those gaps were far smaller on views of the virus as a major threat to the economy. In the current survey, just a 6-point gap separates Republicans and Democrats with this view (20% vs. 26%, respectively) – similar to the 9-point party gap seen in May 2022.

Personal concern about getting or spreading COVID-19

About a quarter of Americans (27%) are very or somewhat concerned about getting a serious case of COVID-19 that would require hospitalization. A somewhat higher share (40%) say they are very or somewhat concerned they might spread the coronavirus to other people without knowing it.

Levels of concern for getting or spreading the coronavirus are about the same as they were in March 2023 and remain down dramatically from early in the pandemic.

The share of Americans who are very or somewhat concerned about getting a serious case is 26 points lower than in November 2020, before a COVID-19 vaccine was available to the public. And the share of Americans who are at least somewhat concerned about spreading COVID-19 without knowing it is down 24 points since November 2020.

Still, the current data shows how the virus remains a concern in daily life for many Americans, more than four years after the first confirmed coronavirus cases appeared in the U.S.

Consistent with past Center surveys, there are demographic and political differences in personal concern about getting a serious case of COVID-19 and unknowingly spreading the virus:

• Income: Lower-income Americans continue to be particularly concerned (38%) about getting a serious case of COVID-19. They’re also more likely than middle- and upper-income Americans to worry about unknowingly spreading COVID-19, but the differences are more modest.
• Party: Democrats (54%) are more than twice as likely as Republicans (24%) to be very or somewhat concerned about unknowingly spreading COVID-19. And they’re 16 points more likely to express concern about getting a serious case of the disease.
• Race and ethnicity: White Americans (20%) are less likely to be concerned about getting a serious case of COVID-19 than Black (43%), Hispanic (39%) and English-speaking Asian Americans (36%).

Some of the groups most personally concerned about getting a severe case of COVID-19 are also among the groups most concerned about the public health threat from the coronavirus. For example, Black adults and adults with lower incomes express more concern about the personal health and public health impact of the coronavirus than White adults and those with upper incomes.

Uptake of the flu shot

The survey finds 44% of U.S. adults say they have gotten a flu shot since August. This share is down slightly from last March, when 49% of Americans said they had recently gotten a flu shot.

Uptake varies by the following factors:

• Age: Older Americans continue to be more likely to report getting the flu shot. Two-thirds of Americans ages 65 and older say they have gotten the flu shot since August. By comparison, only about a third of those under age 50 say the same. These large age differences are seen among both Democrats and Republicans.
• Race and ethnicity: English-speaking Asian Americans (52%) and White Americans (48%) are more likely than Black Americans (38%) and Hispanic Americans (33%) to say they have gotten a flu shot since August. These racial and ethnic differences are consistent with past Center surveys.
• Partisan affiliation: Democrats are more likely than Republicans to say they got a flu shot this year (53% vs. 37%). This 16-point gap is twice as big now as it was in November 2020, during the pandemic’s first year. The current partisan difference in flu shot uptake is similar to the one recorded in March 2023.

The flu shot and updated COVID-19 vaccines are both recommended to protect against severe illness, but Americans approach these vaccines differently.

Americans are more likely to report that they received a flu shot than the updated COVID-19 vaccine this year (44% vs. 28%).

This gap in uptake between the flu shot and updated COVID-19 vaccine is more pronounced among Republicans than Democrats.

Republicans are more than twice as likely to say they’ve gotten a flu shot since August as to say they’ve received an updated COVID-19 vaccine (37% vs. 15%). Among Democrats, this difference is more modest (53% vs. 42%).

Add Pew Research Center to your Alexa

Say “Alexa, enable the Pew Research Center flash briefing”

Report Materials

Table of contents, how the pandemic has affected attendance at u.s. religious services, mental health and the pandemic: what u.s. surveys have found, partisan differences are common in the lessons americans take away from covid-19, what we know about online learning and the homework gap amid the pandemic, americans who relied most on trump for covid-19 news among least likely to be vaccinated, most popular.

About Pew Research Center Pew Research Center is a nonpartisan fact tank that informs the public about the issues, attitudes and trends shaping the world. It conducts public opinion polling, demographic research, media content analysis and other empirical social science research. Pew Research Center does not take policy positions. It is a subsidiary of The Pew Charitable Trusts .

Thank you for visiting nature.com. You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

• View all journals
• My Account Login
• Explore content
• About the journal
• Publish with us
• Sign up for alerts
• Open access
• Published: 28 March 2024

An effective COVID-19 vaccine hesitancy intervention focused on the relative risks of vaccination and infection

• Cameron O’Neill Byerley 1 ,
• Dru Horne 1 ,
• Mina Gong 1 ,
• Stacy Musgrave 2 ,
• Laura A. Valaas 3 ,
• Brian Rickard 4 ,
• Hyunkyoung Yoon 2 ,
• Min Sook Park 5 ,
• Alison Mirin 6 ,
• Surani Joshua 7 ,
• Heather Lavender 1 &
• Sukjin You 5  

Scientific Reports volume  14 , Article number:  7419 ( 2024 ) Cite this article

207 Accesses

1 Altmetric

Metrics details

• Epidemiology
• Patient education

We designed the Relative Risk Tool (RRT) to help people assess the relative risks associated with COVID-19 vaccination and infection. In May 2022 ( N  = 400) and November 2022 ( N  = 615), U.S. residents participated in a survey that included questions about the risks of vaccination and infection. In both cohorts, we found an association between relative risk perception and vaccine hesitancy. Participants in the May cohort were randomly assigned an intervention: to see information from the RRT or the Centers for Disease Control and Prevention (CDC). After the intervention, participants answered the same questions about risk perception and vaccination intent again. The RRT was more effective than the CDC at changing risk perception and increasing vaccination intent. In November, the survey structure was the same, but the RRT was the only intervention included, and we confirmed that the RRT was effective at changing opinions in this new sample. Importantly, the RRT provided accurate information about the risks of serious adverse outcomes to vaccination and still increased vaccination intent. Our work suggests that the RRT helps people assess relative risk, which can in turn help empower them to make informed decisions and ultimately reduce vaccine hesitancy.

Similar content being viewed by others

Revisiting COVID-19 vaccine hesitancy around the world using data from 23 countries in 2021

Jeffrey V. Lazarus, Katarzyna Wyka, … Ayman El-Mohandes

Communicating doctors’ consensus persistently increases COVID-19 vaccinations

Vojtěch Bartoš, Michal Bauer, … Julie Chytilová

Exploratory study of the global intent to accept COVID-19 vaccinations

Alexandre de Figueiredo & Heidi J. Larson

Introduction

COVID-19 vaccine hesitancy is a major global issue 1 , and it is important to develop research-based messaging about vaccination that is broadly understandable and supports decision making 2 . Vaccine hesitancy has been defined in multiple ways, including a “state of indecisiveness regarding a vaccination decision” as well as “delay in acceptance or refusal despite availability of vaccines” 3 . We consider vaccine hesitancy to be reluctance, refusal, or indecision regarding future vaccinations, but consider current vaccination status to be related to vaccine hesitancy. As of May 2023, 70.0% of the world’s population had received at least one dose of a COVID-19 vaccine 4 , 5 , and 17.0% of the U.S. population had received recommended boosters 6 .

People are still making decisions about vaccination 7 and, thus, there is a need for accurate and trustworthy communication about COVID-19 vaccines 8 . Strategies for addressing vaccine hesitancy have been met with mixed success 9 , 10 , 11 , 12 , 13 , 14 , and effective interventions require addressing the various drivers of vaccine hesitancy with multifaceted strategies 9 , 15 , 16 . Reasons for vaccine hesitancy include concern about the risks associated with vaccination, lack of concern for the risk due to the disease, ease of access to vaccination, and mistrust in government and health institutions 8 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 . While reasons for vaccine hesitancy vary widely 25 , 26 , 27 , concern about safety and efficacy are significant reasons across populations. For example, the belief “COVID-19 vaccines are not safe” had the highest odds ratio in a statistical model that predicted vaccine hesitancy 28 . Additionally, all 14 studies in a literature review on vaccine hesitancy found that concerns about safety were associated with hesitancy 29 . In order to address people’s concerns about risks due to vaccination, we focused our research on risk perception and risk communication.

The relative risk tool

Based on our models of citizens’ mathematical thinking from prior mathematics education research and interviews conducted about COVID-19 30 , 31 , 32 , 33 , 34 , we created the RRT to help citizens compare the risks associated with COVID-19 infection with risks associated with more familiar situations such as driving, pregnancy, sports, and other events 35 . We designed, tested, and updated the Relative Risk Tool from August 2020 to May 2022 to help people understand the risks associated with COVID-19 vaccination and infection and the efficacy of vaccines 35 . Note, we will use the phrase “risk of vaccination” throughout this paper to mean “risks associated with vaccination” and likewise for infection. We were inspired to create the RRT based on research we conducted in April and May 2020 on people’s understanding of risk associated with COVID-19 infection 36 . The RRT (Fig.  1 ) uses bar graphs to convey that infection is more likely than vaccination to cause hospitalization and death for all ages modeled, that vaccination reduces the risks due to infection substantially, and that unvaccinated adults face more risk from infection than people are typically willing to accept as a part of daily life. The RRT incorporates an epidemiological model 37 that allows participants to move a slider to find the average risk of hospitalization and death if an average person of a particular age was infected with COVID-19. The RRT shows both relative risk and absolute risk due to infection and vaccination.

The Relative Risk Tool ( https://www.covidtaser.com/relativerisk ) is an interactive web app that allows users to compare the risks associated with various scenarios and COVID-19 infection after inputting their age. For example, 1.6% of mountaineers who climb above base camp at Mount Everest die, which is similar to the risk of death for an unvaccinated 66-year-old infected with COVID-19.

The design of the RRT was informed by research in mathematics education and risk communication conducted before and during the pandemic 23 , 38 , 39 , 40 , 41 , 42 , 43 , 44 , with the primary aim of making the RRT understandable to most people 35 , 36 , 45 , 46 . The RRT provides a potential template for future risk communication tools that can be used to accurately present both absolute and relative risks to the general public using direct comparisons to related risks. Communicating risks for decision making is more difficult than simply telling people probabilities 42 , 47 , 48 , 49 because percentage and probability are difficult concepts to learn, and people hold widely different understandings of the meaning of a particular percentage 30 , 31 , 34 , 50 , 51 , 52 , 53 , 54 . The thinking needed to accurately compare risks is more sophisticated than what is normally developed in K-12 education 55 , 56 , 57 , 58 , 59 , 60 . Experts often quantify risk using percentages 41 , 61 , and the public often uses non-numerical heuristics to estimate risk and to make decisions 62 , 63 , 64 , 65 , 66 , 67 . Many people unconsciously use the availability heuristic 68 , 69 , wherein how easily an event comes to someone’s mind influences their view of how likely that event is to occur. For example, people can readily imagine driving trips and car accidents to develop a sense of the riskiness of driving. We designed the RRT to help people make sense of the percent estimates of risk by relating COVID-19 risks to other more familiar risks like driving 70 .

The presentation format of numerical risks impacts decision making 44 , so it was critical for us to study how people understood the RRT and improve it using an iterative design-based research method. As part of the design process, we analyzed how citizens learned from the RRT using various methods such as interviewing people while using the RRT 46 , conducting online pilot surveys 45 , and thematically categorizing comments on a New York Times article which mentioned the RRT 71 (see “ Methods ” for details). We also updated the RRT in response to requests for more targeted information. For example, we included the risk of myocarditis due to infection and the risk of myocarditis due to vaccination 72 , 73 . The version of the RRT tested in this paper was consistent with the majority of Patient Decision Aid standards with a focus on “presenting probabilities of outcomes in an unbiased and understandable way” to help people understand positive and negative potential outcomes of vaccination 74 . As recommended by the Patient Decision Aid Standards, the RRT also used plain language, disclosed funding, cited peer-reviewed sources of information, and had a systematic development process.

Overview of study

We tested the 2022 version of the RRT (current version available at http://www.covidtaser.com ) in this study. This paper (1) models the relationship between risk perception and COVID-19 vaccination status and intent. This paper, then, (2) evaluates if the RRT intervention, designed specifically to educate about relative risks associated with COVID-19 infection and vaccination, changes participants’ risk perception or intent to be vaccinated. Based on our interviews and prior regression models 8 , we hypothesized that beliefs about the relative risks of vaccination and infection would be correlated with vaccination status and future vaccination intent. Therefore, we also hypothesized that education about relative risks of vaccination and infection would help people resolve indecision about vaccination and increase their willingness to accept future vaccines. To understand the impact of the RRT, we conducted an online pre-post exposure study in May and November 2022 with U.S. adult residents, outlined in Fig.  2 . In May, half of the participants saw information from the RRT, and the other half constituted a control group that was randomly assigned to see similar information about safety and efficacy of the COVID-19 vaccine from the CDC website (see supplementary materials ). All study participants answered demographic questions, questions about risk (inspired by our earlier interviews), and questions from two large studies on vaccination intent 8 , 75 . We assessed the causal impact of information about safety and efficacy on two dimensions: (1) Belief about the relative risk of COVID-19 vaccination and infection and (2) Intent to receive a COVID-19 vaccine in the future. By May 2022, both the Pfizer and Moderna vaccines were fully approved by the U.S. Food and Drug Administration and freely available to all adults. Because the May survey demonstrated larger effects with the RRT than the CDC, and because we wanted to be able to analyze effects of the RRT in subgroups, we opted to not assign participants to view the CDC website in November.

Design of study. All participants were given questions pre-exposure to the intervention about their vaccination status, intention to be vaccinated, and questions about risk. Post exposure participants were asked about vaccination intent, relative risk, and demographics. The questions are abbreviated and labeled in this figure (V-1, RP-1, etc.) with full questions available in supplementary materials and further description in “ Methods ” section.

Sample characteristics

We surveyed U.S. residents using Prime Panels, which samples from a population similar to the U.S. population 76 . The surveys were conducted on May 24, 2022 ( N  = 400) and November 11, 2022 ( N  = 615). Supplementary Table 1 provides information on the sample demographics with the self-reported age, education level, gender, race, ethnicity, political affiliation, COVID-19 infection history, and COVID-19 vaccination status. There are no statistically significant differences in participants’ demographics between the May and November samples.

U.S. residents’ risk perceptions

Table 1 displays results of pre-intervention questions about risk perception.

Many participants dramatically overestimated the number of U.S. citizens who have died as a result of vaccination (Table 1 ). Figure  3 shows non-vaccinated participants are much more likely than vaccinated participants to think vaccination is equally or more risky than infection.

This figure shows the percentage of people with a given COVID-19 vaccination status who gave a particular answer to the question “What is more risky for you?” The left bar in each pair is from May 2022 (N = 400), and the right bar is from November 2022 (N = 615). There was a statistically significant relationship between risk perception and vaccination status, May, \({\chi }^{2}\) (9, N = 400) = 149.05, p < 0.001, W = 0.61; November, \({\chi }^{2}\) (9, N = 615) = 189.75, p < 0.001, W = 0.56.

Most participants gave numerical risk estimates (due to both vaccination and infection) much higher than those estimated in peer-reviewed literature 37 (Fig.  4 ). We also asked: “If you got a COVID-19 vaccine, how concerned would you be about a serious adverse reaction to the vaccine?” and “If you were infected with COVID-19, how concerned would you be about getting hospitalized?” The level of concern participants attached to a given risk estimate varied widely (Fig.  4 ). Many of the participants who estimated their risk of hospitalization if infected at 50% answered that they would be “not at all”, “slightly”, or “somewhat” concerned if infected. Risk estimates of 50% are common (50% Vaccination risk: May, n  = 74/400; November, n  = 115/615; 50% Infection risk: May, n  = 77/400; November, n  = 115/615). Some of these responses might be explained by prior research that found that people often give 50% probability estimates to indicate general uncertainty, whether that be uncertainty about specific frequencies or the belief that the event in question’s occurrence is up to chance 34 , 51 . In other words, someone estimating 50% does not necessarily mean that they believe that an event will occur roughly half the time 34 , 51 .

The figure shows the relationship between people’s percent risk estimates and their associated level of concern. We asked “If you receive a COVID-19 vaccine/booster in the future, what do you think your percent risk of a serious adverse reaction would be? An example of a serious adverse reaction is an allergic reaction requiring treatment in a hospital. Do not include your risk of common side effects such as fatigue” and “If you were infected with COVID-19 (without any vaccination), what do you think your percent risk of hospitalization from COVID-19 would be?” The width of the bars is proportional to the number of respondents who selected a response in each category. Figure d, for example, shows that more people selected a response between 51 and 100% than between 0 and 1%. The colors of the bar indicate the level of concern assigned by the participants for a given risk estimate. For example, in Figure d, half of people who estimated the risk of hospitalization from infection between 0–1% were “not at all concerned” (this is reflected in the light grey bar being a height of 1/2).

Although the median estimates for risk due to infection (May 26%; November 38%) were higher than median estimates for risk due to vaccination (May 20%; November 15%), the median responses were the same order of magnitude for both risks. In contrast, for an unvaccinated 40 year old person, the chance of hospitalization from COVID-19 infection (1.42%) is roughly 6000 times as large as the chance of a severe allergic reaction to the Pfizer COVID-19 vaccine (0.00021%) 37 , 77 .

Risk perceptions are correlated with vaccination intent

We quantified the impact of risk perception on vaccination intent while controlling for other variables commonly associated with vaccination intent (see Fig.  2 for intent question and control variables). The adjusted odds ratios shown in Fig.  5 tell us how many times as likely it is for someone with a given trait to be one level higher in vaccination intent than a person in the associated reference category.

Correlates of COVID-19 vaccination intent include beliefs about the risks associated with COVID-19 vaccination and COVID-19 infection, beliefs about vaccine efficacy, political beliefs, and education. We chose the predictors in the initial full model and the reduced model presented based on the procedure described in the “ Methods ”. The multivariable ordinal logistic regression predicts vaccination intent, May, \({\chi }^{2}\) (11, N = 400) = 299.95, p < 0.001; November, \({\chi }^{2}\) (11, N = 615) = 386.83, p < 0.001. See Supp. Table 6 for exact values of aOR and 95% confidence intervals.

Overall, participants’ beliefs about the risks and benefits of COVID-19 vaccination are correlated with future vaccination intent. Participants who said that vaccination is equally or more risky than infection were less sure about receiving a vaccine in the future than participants who said infection is riskier than vaccination. Consistent with these findings, participants who were concerned about severe adverse reactions to vaccination were less likely to intend to get more vaccination shots, and participants who were more concerned about COVID-19 infection were more likely to intend to be vaccinated in the future. Participants who did not think (or were not sure) that the vaccine reduces risk due to COVID-19 infection were less likely to intend to be vaccinated. The odds ratios show that intent is more strongly associated with beliefs about relative risk than intent is associated with education (which was only statistically significant in November). Additionally, there was no statistically significant association between intent and age, gender, ethnicity, or race (which were therefore removed from the models). See Fig.  5 and Supp. Table 6 for adjusted odds ratios.

RRT impacted beliefs about relative risk

Respondents were asked to express their beliefs on whether COVID-19 vaccination or infection posed a higher risk for them. These beliefs were collected both before and after their visit to the CDC website or RRT tool (for questions, see Fig.  2 , and for responses, see Fig.  6 ).

This diagram shows participants' responses to the question “What is riskier for you?” before and after seeing the CDC ( a ) and the RRT ( b , c ). Blue flows indicate a significant result at p < 0.05. Supplementary Tables 2 and 3 includes include statistics used to create diagram.

We used a McNemar–Bowker test to analyze symmetry in dependent responses 78 . A non-symmetrical response indicates a significant net change from one response pre-intervention to a different response post-intervention, i.e., that participants changed their mind in a specific direction after viewing the intervention. For respondents who viewed the CDC website in May, the global test was non-significant ( p  = 0.681) indicating symmetrical responses (i.e., the number of respondents who changed from one option to another was not significantly different than the converse). For respondents who viewed the RRT tool in May and November, the overall test was significant, and there was a medium effect size (May, p  = 0.001, g  = 0.23, 95% CI [0.17, 0.35]; November, p  < 0.001, g  = 0.16, 95% CI [0.11, 0.23]).

Post-hoc pairwise symmetry tests were conducted, and adjusted p values were calculated using the Benjamini–Hochberg procedure (see Fig.  6 and Supplementary Table 2 ). In Fig.  6 , the blue flows indicate that a significantly greater number of participants changed their responses in the direction of the flow than the converse direction. In May for the RRT, the pairwise tests showed a significant change from participants selecting “COVID-19 infection and vaccination are equally risky” to “COVID-19 infection” as well as from “I don’t know” to “COVID-19 infection”. In November, there were significant changes from participants selecting “COVID-19 infection and vaccination are equally risky” to “COVID-19 infection,” from “I don’t know” to “COVID-19 infection”, and from “Vaccination is more risky” to “COVID-19 infection and vaccination are equally risky.” In May, 48.8% of participants thought infection was riskier than vaccination before seeing the RRT, and this changed to 62.0% post-intervention. In November, 54.5% thought infection was riskier than vaccination before seeing the RRT, and this changed to 61.6% post-intervention (see Supplementary Table 3 for confidence intervals for percentages).

RRT increased intent to accept vaccination

Before and after seeing information from either the CDC or RRT, we asked participants to rate their future intent to be vaccinated (Fig.  7 ). People who were already up to date on vaccinations were asked if they would get an additional booster if it was recommended. In a global test of symmetry, there were statistically significant effects of both the CDC intervention ( p  = 0.004, g  = 0.23 , 95% CI [0.17, 0.36]) and the RRT intervention (May, p  < 0.001, g  = 0.28, 95% CI [0.20, 0.39]); November, p  < 0.001, g  = 0.22, 95% CI [0.18, 0.29]).

This figure shows citizens' responses to a question about intent to be vaccinated in the future before and after seeing the CDC ( a ) and the RRT ( b , c ) information about vaccination side effects and efficacy. Blue flows indicate a significant result at p < 0.05. Supplementary Tables 4 and 5 include statistics used to create diagram.

Post-hoc pairwise symmetry tests were conducted and adjusted p values were calculated using the Benjamini–Hochberg procedure (see Fig.  7 and Supplementary Table 4 ). In Fig.  7 the blue flows are significantly larger than the corresponding flows in the converse direction. There was a significant change from participants selecting “No, definitely not,” before intervention to selecting “Unsure, lean no” after seeing the CDC information. After seeing the RRT, there was a significant change from selecting “No, definitely not,” to selecting “Unsure, lean yes” as well as from “Unsure, lean no” to “Unsure, lean yes” in both the May and November surveys. Additionally, in November there was a significant change from “No definitely not” to “Unsure, lean no” after seeing the RRT. After seeing the CDC information, the percentage of people who claimed they would “definitely not” be vaccinated decreased from 25.3 to 16.1%. After seeing the RRT, the percentage of people who claimed they would “definitely not” be vaccinated decreased from 25.3 to 16.3% in May and from 25.2 to 15.4% in December (see Supplementary Table 5 for confidence intervals for percentages). Although the RRT had a similar impact as the CDC on reduction in participants who responded “No, definitely not”, only participants exposed to the RRT had a statistically significant increase in responses of “Unsure, lean yes”.

It is important to empower people to assess the risks and benefits of vaccination in a way that is evidence-based, mathematically rigorous, and consistent with real-world data. Interventions must be designed with drivers of vaccine hesitancy in mind to be successful 15 . The RRT is tailored to address concerns about safety and efficacy, and we recommend using the RRT as part of an educational program that considers multiple factors driving vaccine hesitancy.

Consistent with previous studies 24 , the extent to which individuals perceived risks and benefits associated with vaccination emerged as an important factor in predicting COVID-19 vaccine hesitancy. The regression model predicted that people who were more concerned with risks associated with infection are more willing to accept future vaccinations, and people who are more concerned with the risks associated with vaccination are less willing to accept additional vaccinations. People who are uncertain or do not believe vaccination reduces the risk of serious outcomes from infection are less willing to receive future vaccinations. Further, many participants, including those with vaccinations, dramatically overestimated their percent risk of a serious adverse outcome to vaccination and the number of U.S. citizens who have died from vaccination. The combination of participants’ difficulties in assessing risk and the strength of the relationship between risk perceptions and vaccination intent suggests that education around risk has the potential to reduce vaccine hesitancy.

Because most people have limited ability to interpret percentages and decimals in health contexts, careful design of communication regarding numerical information is critical 66 . We designed the RRT to convey the relative risk of COVID-19 vaccination versus infection and the efficacy of vaccination in a way that allowed the general population to compare and comprehend the relative sizes of percentages. The CDC website also provides information about the efficacy of vaccination and the low risk posed by vaccination; however, the information often appears in formats (e.g., fractions and Cartesian coordinate systems) that are known in mathematics education to be hard to understand 30 , 32 , 79 , 80 . As such, it was not surprising that individuals shown the images from the CDC website did not have a statistically significant change in belief about relative risk even though their initial belief misaligned with the numerical information provided. In contrast, the RRT was more effective in changing participants’ beliefs about the relative risk of COVID-19 infection and vaccination. After seeing the RRT, there was a statistically significant shift from responding “infection and vaccination are equally risky” or “I don’t know” to “infection is riskier.”

Both the CDC and RRT had a positive effect on intent to accept COVID-19 vaccination. Even though both the CDC and the RRT conveyed that there are rare but serious risks associated with COVID-19 vaccination, there were no statistically significant decreases in intent to vaccinate. Both conveyed that vaccination reduced risk, but vaccinated individuals could still have severe outcomes from infection. This finding is useful because of the ethical importance of communicating honestly about the magnitude of a health intervention’s effectiveness along with the risks of an intervention to the public 81 , 82 .

It is challenging to design an online intervention that results in a change in vaccination intent, and many (but not all) interventions studied had no statistically significant impact or had impact only in some subgroups 75 , 83 , 84 , 85 , 86 , 87 , 88 . A few interventions had positive statistically significant impact on vaccine hesitancy 13 , 89 , 90 , 91 . A 2023 meta-analysis of 71 behavioral interventions targeting vaccine hesitancy found a small, but statistically significant, overall effect size 92 . Although the RRT and CDC information was effective at increasing intent to vaccinate, it did not significantly increase the number of people who were “definitely” intending to accept a vaccine. These gains in intention to vaccinate are still noteworthy for an online intervention that took participants on average between nine and ten minutes. The most effective educational interventions about vaccines used multiple strategies 15 , and we suspect, based on our interviews on the RRT, that one-on-one conversations using the RRT would better support decision making. Attempts to address misinformation about the COVID-19 vaccines have been most effective when using the following strategies: conveying the weight of evidence, utilizing humor, tailoring communications to target audiences, and incorporating warnings about misinformation 9 .

We also suspect that one-on-one conversations about relative risk with a trusted source could increase the impact of the RRT and CDC information because trust in government, health care providers, and the scientific process is related to vaccine hesitancy 93 . We acknowledge that mistrust in health care organizations and governments has a valid historical rationality, given prior U.S. government atrocities done in the name of medical research, especially against minoritized groups 93 . Although participants were provided links to the peer-reviewed sources on the RRT and told that the RRT appeared on national television and in the Scientific American , we understand that an online tool is not necessarily a highly credible source. After seeing either the CDC or RRT, we asked participants if the information seemed trustworthy. After seeing the RRT tool 81.7% (May) and 78% (November) responded “Yes, definitely” or “Unsure, lean yes.” In May, 72.4% of participants assigned to the CDC responded “Yes, definitely” or “Unsure, lean yes.” This study does not analyze the relationship between trust in information and change in intent after seeing information or the impact of information when conveyed by a trusted source; however, this is an important future consideration.

Several limitations impact the generalizability and applicability of research. The sample, while diverse, only includes U.S. adults with computer access who self-selected to participate in online surveys for monetary compensation. Although previously found to be reflective of the general U.S. population, research is ongoing about the representativeness of Prime Panels samples with regards to risk perceptions and health decision making 94 . Participants in our study provided similar percent risk estimates of hospitalization due to COVID-19 infection as participants in a larger, nationally representative survey of U.S. residents 95 . Paid online surveys allow for the collection of data from large groups, but it is impossible to guarantee all participants understood survey questions as intended or to draw strong conclusions about the reasons for their answers. Further, the COVID-19 global pandemic has been a continuously evolving health crisis since its onset in late 2019. The external influences on participants’ beliefs and decision making that we captured in our surveys are likely continually evolving, and this study does not attempt to quantify change in beliefs. We tested the RRT at two time points to gather stronger evidence of its effectiveness as opposed to studying change in beliefs over time. Finally, although the authors attempted to perform an unbiased a review of the data, our personal beliefs in the public good of widespread vaccination against COVID-19 may have introduced bias.

Early in the pandemic, a variety of risk calculators were rapidly created to help citizens understand COVID-19 risk and seen by millions of people 96 , 97 , 98 , 99 . Most widely-used COVID-19 risk calculators display people’s risk percentages without comparison to other risks. The risk percentages displayed are far lower than most U.S. residents’ estimates, and people struggle to make sense of small probabilities 44 . The research from this study of the RRT demonstrates how carefully communicating the relative risks of vaccination and infection, as well as designing communication tools with attention to prior research in mathematics education and risk communication, can reduce vaccine hesitancy.

Future directions for additional research are multifaceted. These include exploring the perceived trustworthiness of the RRT and the impact this has on effectiveness, testing the RRT in various real-world settings such as in-person with a healthcare provider, and measuring real-world outcomes to see if the RRT has an impact on the number of vaccinations received. It would be useful to compare the RRT across additional populations; a survey we conducted in South Korea showed the RRT had a larger impact in South Korea (in preparation). We also wonder about the impact of risk calculators portraying substantially lower risk estimates than users’ initial overestimates and whether this makes individuals more complacent about the risks of infection, as complacency about risk of disease is relevant to vaccine hesitancy 22 .

Because of the critical importance of vaccination for personal risk reduction and public health, alongside the ethical responsibility to disclose side effects of any medical intervention, additional research into and development of risk communication tools should be pursued.

Survey participants and sampling

Prime Panels are used to collect random human subjects data in multiple fields, including social and behavioral sciences 76 , 100 . By using Prime Panels, we were able to acquire a diverse and randomly selected sample from their participant pool, which is known to be reasonably representative of the U.S. population 76 . It should be noted that our sample had more women than the U.S. average, and a slightly different distribution of races than the U.S. as a whole. The average age of Prime Panel participants aligns with the U.S. average, and age significantly impacts COVID-19 risk. They were paid 1.50 USD for a survey that was completed on average in 9.1 min in May and 10.3 min in November. The payment, research procedures, and survey were approved by the University of Georgia Institutional Review Board with reference number PROJECT00002145. All research conducted followed the approved procedures and University of Georgia human subjects research guidelines and regulations. All participants were over 18 years old and gave informed consent before participating in research.

Surveying participants in May and November allowed us to determine if the RRT had a similar impact on a new sample of participants with 6 months more exposure to information. Public opinion about COVID-19 and its vaccine was highly politicized and shifted dramatically throughout the pandemic in the U.S. 101 . The safety and efficacy of a new bivalent booster was presented in Fall 2022 102 . Information about the risks of vaccination and new variants of COVID-19 were common in the news during those 6 months. For example, on October 7th, 2022 the state of Florida issued widely critiqued guidance recommending against COVID-19 mRNA vaccination in males ages 18 to 39 due to the risk of myocarditis caused by vaccination 103 .

Survey questions

Participants took a 29-question online survey. Participants were asked if they had been infected with COVID-19, how many COVID-19 vaccinations (if any) they had, and why they were vaccinated (V-1 to V-2). Nine questions asked participants about their perceptions of risk associated with COVID-19 infection and vaccination including if they thought vaccination decreased risk due to infection (RP-0 to RP-8). We knew from pilot surveys that many participants thought vaccination and infection were equally risky, so we added follow up questions to see if they thought equal numbers of people have died due to vaccination and infection to better understand what they meant by “equally risky.” One question was a mathematical word problem about disease involving finding 10% of 1000 (RL-1), and six questions were about demographics (D-1 to D-6). As part of the survey, participants were randomly assigned to see information about risks and benefits of vaccination from either the CDC or the RRT and were asked questions related to the intervention (RRT-1 to RRT-11 or CDC-1 to CDC-12).

The survey questions were inspired by previous international surveys 8 , 75 , online pilot surveys with small samples 45 , 46 , and our interviews with U.S., South Korean, and Kenyan residents about COVID-19 infection and vaccination risk 36 . See Supplementary Table 7 for dates, sizes and citations associated with pilot surveys. The analysis of the pilot survey informed decisions on questions to include in the survey of a larger sample. We categorized open-ended responses to questions on the pilot surveys to create multiple-choice options on the survey for this study (Supplementary Figs.  1 – 3 ). We also used similar questions (RP-0, RP-2) to another research group 8 , 104 who used an expert panel and comprehensive literature review to develop their 23-country survey on vaccine hesitancy. Their survey was used in the U.S. and informed by internally and externally validated surveys about COVID-19 105 . Additionally, some questions (V-1, RRT-11, and CDC-12) had similar wording as a prior study 75 that asked participants in the U.S. and U.K. about intent to be vaccinated before and after seeing misinformation. To keep the survey to a manageable length, we intentionally focused our questions on participants’ perceptions of vaccine safety and efficacy and collected basic demographic information relevant to vaccine hesitancy (age, race, ethnicity, gender, education level, and political beliefs). Participants were allowed to select a race or races, ethnicity, and gender from multiple choice options or write in their preference. Multiple choice options were designed to be inclusive and use bias-free language as recommended by APA. Since prior research 8 indicates that trust is an important factor in vaccine hesitancy, we asked a question about how trustworthy the participants found the CDC and the RRT information. Although access to vaccination is a critical global issue 106 , during the study period, COVID-19 vaccinations were provided free of charge by the U.S. government, regardless of insurance status, and thus we did not ask about access. We piloted the questions multiple times in interviews and small samples on Prime Panels and had experts in item design review the wording for clarity before the larger May and November samples. In order to use the most familiar wording, we used the term COVID-19 instead of SARS-COV-2 on survey questions.

CDC and RRT intervention in survey

In May individuals were randomly assigned to see similar (but not identical) information presented by the CDC or RRT. Information from both the CDC and the RRT images stated that there are serious but extremely rare adverse events after vaccination, but each presented the information using different representations of data. We used the CDC estimates of the risk of particular adverse events in the design of the RRT and graphed the percentages provided by the CDC for comparison with other risks. We focused participants on particular parts of the CDC website or the RRT by embedding screenshots of the most relevant information into the survey and asking questions about the images before providing participants with the links to the content online. See images in survey instrument in supplementary materials . In addition to images, participants were provided with a short video about the RRT and a link to a video by the CDC.

Information from the CDC included graphs of the rates of COVID-19 hospitalizations for vaccinated and unvaccinated adults, statements about how many times as many unvaccinated adults were hospitalized due to COVID-19 as vaccinated adults, and information about rare side effects of vaccination such as anaphylaxis, thrombosis, myocarditis, and pericarditis. The CDC information said the vaccines were safe and effective and had been given to hundreds of millions of people, and the CDC also explained that the booster shots can enhance or restore protection that wanes after time. In addition to being provided with images of and links to the CDC website, participants were asked to answer questions about the CDC information to encourage reading the information and to check for comprehension. For example, we asked “According to the CDC, which is more risky for a young, healthy adult?” underneath a screenshot of relevant information. The graphics used by the CDC were significantly more complicated to understand than those recommended for use in health communication 39 .

Survey participants assigned to the RRT received a link to the full tool, but the survey also included specific screenshots of the RRT designed to highlight the relative risk of vaccination and infection and the reduction in risk due to vaccination. For example, we asked participants to compare the risk of death from COVID-19 if infected for a vaccinated and unvaccinated 76-year-old. The graphic included the absolute risk if infected but was designed to help people focus on relative risk. Another question asked participants to use an image of the RRT to compare the risk of hospitalization if infected with COVID-19 to the chance of a severe allergic reaction to the vaccine. Finally, we asked participants a question based on an image showing the risk of being hospitalized if infected for someone vaccinated over 6 months ago, someone vaccinated and boosted, and someone who is unvaccinated. Unlike the CDC website, the RRT provided no direct medical advice. The RRT did not say vaccination was safe and effective, provided no recommendations to get vaccinated or boosted, and did not recommend any particular behaviors with regard to mitigating COVID-19 infection risk.

After viewing the assigned intervention, we asked participants what they thought was riskier, if the information they saw was trustworthy, and whether they wanted to be vaccinated in the future. Based on these results, we found the RRT to be more effective than the CDC materials, so in November 2022, we assigned everyone to the RRT to gather further data about effectiveness.

Refinement of the relative risk tool

In April and May of 2020, we interviewed 25 U.S. and 7 South Korean citizens about their mathematical understandings of quantitative representations of COVID-19 data that were ubiquitous in the media 36 . We conducted additional interviews from November 2020 to June 2022 and used a design-based research methodology 107 to iteratively improve the RRT by incorporating feedback from the interviews and experts in public health and mathematics education. We conducted 14 interviews with U.S. residents, 10 with South Korean residents, and 9 with Kenyan residents. The interview sample was not representative, but it was diverse with respect to age, education, political affiliation, citizenship, income, and profession, which allowed us to iteratively improve the RRT. In the interviews we conducted after adding information about risks and efficacy of vaccination to the RRT, we found viewing the relative risk of vaccination versus infection and the reduction in risk due to vaccination resulted in people being more willing to be vaccinated.

We knew from prior research, interviews, and pilot surveys that citizens thought a risk of death of 1% or 2% was small, so we intentionally designed the RRT to help them understand the magnitude of those risks by comparing the risks to other situations. We knew from prior research 58 and our interviews on RRT that some people think a decimal such as 0.0002 is larger than a decimal such as 0.02 because it has more digits, mirroring the fact that among whole numbers, larger numbers have more digits. Even highly educated people can struggle to determine if a 1, 5, or 10% risk of getting a disease is larger 59 . Previous research shows people especially struggle to make sense of low-probability risks 44 .

Estimating and communicating risks about COVID-19 accurately is complicated by several issues. One, the risk due to COVID-19 infection increases exponentially with age; for instance, an average 85-year-old is about 19,000 times as likely to die if infected than a 10-year-old 37 . Two, although it is possible to roughly compare the likelihood of one adverse outcome due to infection to one (different) adverse outcome due to vaccination, it is essentially impossible to compare the likelihood and seriousness of all risks posed by infection to all risks posed by vaccination. For instance, a severe allergic reaction to vaccination might be more or less serious than a hospitalization due to infection.

There are limitations of the statistical estimates provided on the RRT. Vaccination risk estimates are based on the information available and vary for different strains of SARS-COV-2, the differences of efficacy of vaccinations based on the strain, time since vaccination, and immune system response. COVID-19 infection risks are provided based on peer reviewed studies; however, the risk of infection changed over the course of the pandemic as knowledge about COVID-19 evolved and more treatment recommendations became available as well as with variations in local health care system capacity and preparedness. The risk percentages are averages, but there are differences in risk for people with various medical conditions, and only a few specific medical conditions are on the RRT. Further, it is much more challenging to quantify the likelihood and level of impact of non-acute risks such as long-COVID, the effectiveness of vaccination against long-COVID, and long-COVID-like symptoms triggered by vaccination 108 , 109 , 110 . The risk of death from COVID-19 is based on a particular population used to create the model and varies by access to medical care and general health of a population. In designing the RRT, we were constantly faced with the difficulty of providing risk estimates in an easy-to-understand manner, knowing that various peer-reviewed studies had different estimates.

We determined the sample size for the May 2022 survey using a power analysis for binary logistic regression. This was calculated with G*Power software. We chose a larger sample size in November because there were some interesting relationships in subgroups of original vaccination intent that we wanted to investigate in a larger sample. The sample size was much larger than needed to detect the relationships we focused on, but is not large enough to study the differential impact of RRT in different subgroups.

To create a model to predict vaccination status, which involves a series of vaccine shots, we employed use of ordinal logistic regression for each of the surveys. We used the model:

\(logit\left(P\left(Y\le j\right)\right)={\beta }_{j0}+{\beta }_{j1}{x}_{1}\ldots {\beta }_{jp}{x}_{p}\) for \(j=1,\dots ,J-1\) levels of the ordinal variable and p variables. Analyses were conducted using SPSS version 28. We first included responses to 13 survey questions as predictor variables in the model. Decisions about which question to include in the model were inspired from our pilot data, our observations in interviews, and from other research on vaccination hesitancy (see supplementary materials for the survey). The six survey questions about risk included questions about how concerned participants were about both vaccination and infection, what they thought was more risky, how many people they thought had died from either vaccination and from infection, and whether or not they thought the vaccination reduced risk of serious outcomes from infection. The six demographic predictors were race, ethnicity, age, gender, political party, and education level. Finally, we included responses to one question about previous COVID-19 infection as a predictor. To increase parsimony, we reduced the number of variables based on statistical significance in the first model and prior empirically demonstrated relationships (e.g., political beliefs and vaccination status). Relationships between intent to vaccinate and the independent variables are reported as adjusted odds ratios and 95% confidence intervals. The assumption of proportional odds was tested for each data set using the test of parallel lines. In each case, the test was not significant, indicating that the coefficients are the same across all response categories. The variance inflation factor (VIF) was calculated for each variable to test for multicollinearity. The assumption of no multicollinearity is met with VIF values below 3 for each variable.

The McNemar–Bowker test 78 of symmetry was used to analyze the change in respondent’s perceptions of risk of vaccination and infection, as well as intent to receive a COVID-19 vaccination. These analyses were conducted using R 4.3.0 and the rcompanion package.

Data availability

The data from the May 2022 and November 2022 survey are available to download at http://www.covidtaser.com . Some participants took fewer than 3 min to complete the survey. After group discussion, the authors decide to exclude these responses from the analysis because such participants did not take sufficient time to read the questions and look at the CDC or RRT information.

Code availability

The code for the McNemar–Bowker tests and the data used in SPSS 28 to create the regression model is available at http://www.covidtaser.com .

Sallam, M. COVID-19 vaccine hesitancy worldwide: A concise systematic review of vaccine acceptance rates. Vaccines 9 , 160 (2021).

Article   CAS   PubMed   PubMed Central   Google Scholar  

Attwell, K., Hannah, A. & Leask, J. COVID-19: Talk of ‘vaccine hesistancy’ lets govenerments off the hook. Nature 602 , 574–577 (2022).

Article   ADS   CAS   PubMed   Google Scholar  

Bussink-Voorend, D., Hautvast, J. L., Vandeberg, L., Visser, O. & Hulscher, M. E. A systematic literature review to clarify the concept of vaccine hesitancy. Nat. Hum. Behav. 6 , 1634–1648 (2022).

Article   PubMed   Google Scholar  

Our World in Data: Coronavirus (COVID-19) Vaccinations . https://ourworldindata.org/covid-vaccinations (2023).

Mathieu, E. et al. A global database of COVID-19 vaccinations. Nat. Hum. Behav. 5 , 947–953 (2021).

Centers for Disease Control and Prevention. COVID Data Tracker. https://covid.cdc.gov/covid-data-tracker (2023).

Moehring, A. et al. Providing normative information increases intentions to accept a COVID-19 vaccine. Nat. Commun. 14 , 126 (2023).

Article   ADS   CAS   PubMed   PubMed Central   Google Scholar  

Lazarus, J. V. et al. Revisiting COVID-19 vaccine hesitancy around the world using data from 23 countries in 2021. Nat. Commun. 13 , 3801 (2022).

Whitehead, H. S., French, C. E., Caldwell, D. M., Letley, L. & Mounier-Jack, S. A systematic review of communication interventions for countering vaccine misinformation. Vaccine 41 , 1018–1034 (2023).

Article   PubMed   PubMed Central   Google Scholar  

Li, P. C. et al. Impact of an education intervention on COVID-19 vaccine hesitancy in a military base population. Mil. Med. 187 , e1516–e1522 (2022).

Article   Google Scholar  

Abdel-Qader, D. H. et al. Pharmacists-physicians collaborative intervention to reduce vaccine hesitancy and resistance: A randomized controlled trial. Vaccine: X 10 , 100135 (2022).

PubMed   Google Scholar  

Talmy, T., Cohen, B., Nitzan, I. & Ben Michael, Y. Primary care interventions to address COVID-19 vaccine hesitancy among Israel Defense Forces soldiers. J. Community Health 46 , 1155–1160 (2021).

Johnson, V. et al. The ‘Fauci Effect’: Reducing COVID-19 misconceptions and vaccine hesitancy using an authentic multimodal intervention. Contemp. Educ. Psychol. 70 , 102084 (2022).

Freeman, D. et al. COVID-19 vaccine hesitancy in the UK: The Oxford coronavirus explanations, attitudes, and narratives survey (Oceans) II. Psychol. Med. 52 , 3127–3141 (2022).

Jarrett, C., Wilson, R., O’Leary, M., Eckersberger, E. & Larson, H. Strategies for addressing vaccine hesitancy—A systematic review. Vaccine 33 , 4180–4190. https://doi.org/10.1016/j.vaccine.2015.04.040 (2015).

Peters, M. D. Addressing vaccine hesitancy and resistance for COVID-19 vaccines. Int. J. Nurs. Stud. 131 , 104241 (2022).

EURO Working Group on Vaccine Communications (2011).

Kumar, S., Shah, Z. & Garfield, S. Causes of vaccine hesitancy in adults for the influenza and COVID-19 vaccines: A systematic literature review. Vaccines 10 , 1518 (2022).

Dror, A. A. et al. Vaccine hesitancy: The next challenge in the fight against COVID-19. Eur. J. Epidemiol. 35 , 775–779 (2020).

Troiano, G. & Nardi, A. Vaccine hesitancy in the era of COVID-19. Public Health 194 , 245–251 (2021).

Article   CAS   PubMed   Google Scholar  

Pires, C. Global predictors of COVID-19 vaccine hesitancy: A systematic review. Vaccines 10 , 1349 (2022).

Betsch, C. et al. Beyond confidence: Development of a measure assessing the 5C psychological antecedents of vaccination. PLoS One 13 , e0208601 (2018).

Warren, G. W. & Lofstedt, R. COVID-19 vaccine rollout risk communication strategies in Europe: A rapid response. J. Risk Res. 24 , 369–379. https://doi.org/10.1080/13669877.2020.1870533 (2021).

Wong, J. C. S. & Yang, J. Z. Comparative risk: Dread and unknown characteristics of the COVID-19 pandemic versus COVID-19 vaccines. Risk Anal. 42 , 2214–2230 (2022).

Eskola, J., Duclos, P., Schuster, M. & MacDonald, N. E. How to deal with vaccine hesitancy?. Vaccine 33 , 4215–4217 (2015).

Lee, M. & You, M. Direct and indirect associations of media use with COVID-19 vaccine hesitancy in South Korea: Cross-sectional web-based survey. J. Med. Internet Res. 24 , e32329 (2022).

Nguyen, L. H. et al. Self-reported COVID-19 vaccine hesitancy and uptake among participants from different racial and ethnic groups in the United States and United Kingdom. Nat. Commun. 13 , 636 (2022).

Fajar, J. K. et al. Global prevalence and potential influencing factors of COVID-19 vaccination hesitancy: A meta-analysis. Vaccines 10 , 1356 (2022).

Solís Arce, J. S. et al. COVID-19 vaccine acceptance and hesitancy in low-and middle-income countries. Nat. Med. 27 , 1385–1394 (2021).

Steffe, L. P. & Olive, J. Children’s Fractional Knowledge (Springer, 2010).

Book   Google Scholar  

Bradshaw, L., Izsák, A., Templin, J. & Jacobson, E. Diagnosing teachers’ understandings of rational numbers: Building a multidimensional test within the diagnostic classification framework. Educ. Meas. Issues Pract. 33 , 2–14 (2014).

Moore, K. C. In Transfer of Learning: Progressive Perspectives for Mathematics Education and Related Fields (eds Hohensee, C. & Lobato, J.) 145–171 (Springer, 2021).

Chapter   Google Scholar  

Moore, K. C. & Thompson, P. W. In Proceedings of the 18th Meeting of the MAA Special Interest Group on Research in Undergraduate Mathematics Education (eds Fukawa-Connelly, T. et al. ) 782–789 (RUME, 2015).

Google Scholar  

Konold, C. Informal conceptions of probability. Cogn. Instr. 6 , 59–98 (1989).

Joshua, S. et al. Exploring relative size with relative risk. Math. Teach. Learn. Teach. PK-12 115 , 339–350 (2022).

Yoon, H. et al. United States and South Korean citizens’ interpretation and assessment of COVID-19 quantitative data. J. Math. Behav. 62 , 100865 (2021).

Herrera-Esposito, D. & de Los Campos, G. Age-specific rate of severe and critical SARS-CoV-2 infections estimated with multi-country seroprevalence studies. BMC Infect. Dis. 22 , 311 (2022).

Dubé, E. et al. Vaccine hesitancy: An overview. Hum. Vaccines Immunother. 9 , 1763–1773 (2013).

Ancker, J. S., Senathirajah, Y., Kukafka, R. & Starren, J. B. Design features of graphs in health risk communication: A systematic review. J. Am. Med. Inform. Assoc. 13 , 608–618 (2006).

Collins, A., Florin, M.-V. & Renn, O. COVID-19 risk governance: Drivers, responses and lessons to be learned. J. Risk Res. 23 , 1073–1082 (2020).

Covello, V. T. Social and behavioral research on risk: Uses in risk management decisionmaking. Environ. Int. 10 , 541–545 (1984).

Fischhoff, B. Risk perception and communication unplugged: Twenty years of process. Risk Anal. 15 , 137–145 (1995).

Wood, M. M. et al. Communicating actionable risk for terrorism and other hazards ⋆ . Risk Anal. 32 , 601–615 (2012).

Stone, E. R., Yates, J. F. & Parker, A. M. Effects of numerical and graphical displays on professed risk-taking behavior. J. Exp. Psychol. Appl. 3 , 243 (1997).

Yoon, H. et al. in 44th Annual Meeting of the North American Chapter of the International Group for the Psychology of Mathematics Education. (eds A. Lischka et al. ) 862–871.

Gong, M., Horne, D., Yoon, H. & Byerley, C. In 25th Annual Conference on Research in Undergraduate Mathematics Education.

Fischhoff, B. The realities of risk-cost-benefit analysis. Science 350 , 6516 (2015).

Article   ADS   Google Scholar  

Fischhoff, B. & Broomell, S. B. Judgment and decision making. Annu. Rev. Psychol. 71 , 331–355 (2020).

Siegrist, M. & Árvai, J. Risk perception: Reflections on 40 years of research. Risk Anal. 40 , 2191–2206 (2020).

Behr, M., Lesh, R., Post, T. & Silver, E. In Acquisition of Mathematics Concepts and Processes (eds Lesh, R. & Landau, M.) 91–125 (Academic Press, 1983).

Konold, C. In Radical Constructivism in Mathematics Education. Mathematics Education Library Vol. 7 (ed. Von Glasersfeld, E.) 139–156 (Springer, Paris, 1991).

Probabilistic Thinking: Presenting Plural Perspectives (Springer, 2014).

Batanero, C., Chernoff, E. J., Engel, J., Lee, H. S. & Sánchez, E. Research on Teaching and Learning Probability (Springer, 2016).

Byerley, C. & Thompson, P. W. Secondary mathematics teachers’ meanings for measure, slope, and rate of change. J. Math. Behav. 48 , 168–193 (2017).

Kollosche, D. & Meyerhöfer, W. COVID-19, mathematics education, and the evaluation of expert knowledge. Educ. Stud. Math. 108 , 401–417 (2021).

Bloom, M. A., Fuentes, S. Q. & Crocker, J. How the COVID-19 pandemic reveals gaps in science and mathematics instruction. Electron. J. Res. Sci. Math. Educ. 24 , 1–6 (2020).

Garfield, J. & Ahlgren, A. Difficulties in learning basic concepts in probability and statistics: Implications for research. J. Res. Math. Educ. 19 , 44–63 (1988).

Carpenter, T. P., Corbitt, M. K., Kepner, H. S., Lindquist, M. M. & Reys, R. Results of the second NAEP mathematics assessment: Secondary school. Math. Teach. 73 , 329–338 (1980).

Lipkus, I. M., Samsa, G. & Rimer, B. K. General performance on a numeracy scale among highly educated samples. Med. Decis. Making 21 , 37–44 (2001).

Cokely, E. T., Galesic, M., Schulz, E., Ghazal, S. & Garcia-Retamero, R. Measuring risk literacy: The Berlin numeracy test. Judgm. Decis. Making 7 , 25–47 (2012).

Slovic, P. & Weber, E. U. Regulation of Toxic Substances and Hazardous Waste (Foundation Press, 2013).

Fischhoff, B., Bostrom, A. & Quadrel, M. J. Risk perception and communication. Annu. Rev. Public Health 14 , 183–203 (1993).

Slovic, P. Perception of risk. Science 236 , 280–285 (1987).

Fischhoff, B., Slovic, P. & Lichtenstein, S. In The Analysis of Actual Versus Perceived Risks Vol. 1 (eds Covello, V. T. et al. ) 235–249 (Springer, 1983).

Slovic, P. & Peters, E. Risk perception and affect. Curr. Dir. Psychol. Sci. 15 , 322–325 (2006).

Ancker, J. S. & Kaufman, D. Rethinking health numeracy: A multidisciplinary literature review. J. Am. Med. Inform. Assoc. 14 , 713–721 (2007).

Peters, E. Beyond comprehension: The role of numeracy in judgments and decisions. Curr. Dir. Psychol. Sci. 21 , 31–35 (2012).

Kahneman, D., Slovic, S. P., Slovic, P. & Tversky, A. Judgment Under Uncertainty: Heuristics and Biases (Cambridge University Press, 1982).

Tversky, A. & Kahneman, D. Judgment under uncertainty: Heuristics and biases. Science 185 , 1124–1131 (1974).

Ginsburg, K. R. et al. National young-driver survey: Teen perspective and experience with factors that affect driving safety. Pediatrics 121 , e1391–e1403 (2008).

Mueller, B. New York Times (The New York Times Company, 2022).

Martinez, M. W. et al. Prevalence of inflammatory heart disease among professional athletes with prior COVID-19 infection who received systematic return-to-play cardiac screening. JAMA Cardiol. 6 , 745–752 (2021).

Montgomery, J. et al. Myocarditis following immunization with mRNA COVID-19 vaccines in members of the US military. JAMA Cardiol. 6 , 1202–1206 (2021).

O’Connor, A. et al. International Patient Decision Aid Standards (IPDAS) Collaboration (2005).

Loomba, S., de Figueiredo, A., Piatek, S. J., de Graaf, K. & Larson, H. J. Measuring the impact of COVID-19 vaccine misinformation on vaccination intent in the UK and USA. Nat. Hum. Behav. 5 , 337–348 (2021).

Chandler, J., Rosenzweig, C., Moss, A. J., Robinson, J. & Litman, L. Online panels in social science research: Expanding sampling methods beyond Mechanical Turk. Behav. Res. Methods 51 , 2022–2038 (2019).

Shimabukuro, T. & Nair, N. Allergic reactions including anaphylaxis after receipt of the first dose of Pfizer-BioNTech COVID-19 vaccine. JAMA 325 , 780–781. https://doi.org/10.1001/jama.2021.0600 (2021).

Bowker, A. H. A test for symmetry in contingency tables. J. Am. Stat. Assoc. 43 , 572–574. https://doi.org/10.2307/2280710 (1948).

Mullis, I. V., Dossey, J. A., Owen, E. H. & Phillips, G. W. The State of Mathematics Achievement: NAEP’s 1990 Assessment of the Nation and the Trial Assessment of the States (National Center for Education Statistics, 1991).

Carlson, M. P., Madison, B. & West, R. D. A study of students’ readiness to learn calculus. Int. J. Res. Undergrad. Math. Educ. 1 , 209–233 (2015).

de Barra, M. & Brown, R. C. Public-health communication should be more transparent. Nat. Hum. Behav. 7 , 662–664 (2023).

Brown, R. & de Barra, M. A taxonomy of non-honesty in public health communication. Public Health Ethics 16 , 86–101 (2023).

Freeman, D. et al. Effects of different types of written vaccination information on COVID-19 vaccine hesitancy in the UK (OCEANS-III): A single-blind, parallel-group, randomised controlled trial. Lancet Public Health 6 , e416–e427 (2021).

Batteux, E., Mills, F., Jones, L. F., Symons, C. & Weston, D. The effectiveness of interventions for increasing COVID-19 vaccine uptake: A systematic review. Vaccines 10 , 386 (2022).

Schwarzinger, M. & Luchini, S. Addressing COVID-19 vaccine hesitancy: Is official communication the key?. Lancet Public Health 6 , e353–e354 (2021).

Yuan, S. & Chu, H. Vaccine for yourself, your community, or your country? Examining audiences’ response to distance framing of COVID-19 vaccine messages. Patient Educ. Couns. 105 , 284–289 (2022).

Reddinger, J. L., Levine, D. & Charness, G. Can targeted messages reduce COVID-19 vaccination hesitancy? A randomized trial. Prev. Med. Rep. 29 , 101903 (2022).

Thorpe, A. et al. Communicating about COVID-19 vaccine development and safety. PLoS One 17 , e0272426 (2022).

Mottelson, A. et al. A self-administered virtual reality intervention increases COVID-19 vaccination intention. Vaccine 39 , 6746–6753 (2021).

Plechatá, A. et al. Experiencing herd immunity in virtual reality increases COVID-19 vaccination intention: Evidence from a large-scale field intervention study. Comput. Hum. Behav. 139 , 107533 (2023).

Okuhara, T. et al. Encouraging COVID-19 vaccination via an evolutionary theoretical approach: A randomized controlled study in Japan. Patient Educ. Couns. 105 , 2248–2255 (2022).

Huang, Y., Huang, X. & Yu, R. The effectiveness of nonfinancial interventions and monetary incentives on COVID-19 vaccination: A meta-analysis. Health Psychol. 42 , 411–424 (2023).

Bajaj, S. S. & Stanford, F. C. Beyond Tuskegee—Vaccine distrust and everyday racism. N. Engl. J. Med. 384 , e12 (2021).

Sharma, A. et al. Differences in demographics and behaviors across two web-based survey platforms: Observations from a study of risk perceptions of heated tobacco products (HTPs). Prev. Med. Rep. 33 , 102194 (2023).

Rothwell, J. & Witters, D. U.S. Adults' Estimates of COVID-19 Hospitalization Risk . https://news.gallup.com/opinion/gallup/354938/adults-estimates-covid-hospitalization-risk.aspx (2021).

StarThower. COVIDAge Risk Calculator . https://calculator.covid-age.com (2020).

Nexoid. COVID-19 Survival Calculator . https://www.covid19survivalcalculator.com/en/research (2023).

Mathematica. 19 and Me: Covid-19 Risk Score Calculator . https://www.mathematica.org/dataviz/19-and-me-covid-19-risk-score-calculator (2021).

Chande, A. et al. Real-time, interactive website for US-county-level COVID-19 event risk assessment. Nat. Hum. Behav. 4 , 1313–1319 (2020).

Litman, L., Robinson, J. & Abberbock, T. TurkPrime.com: A versatile crowdsourcing data acquisition platform for the behavioral sciences. Behav. Res. Methods 49 , 433–442 (2017).

Bolsen, T. & Palm, R. Politicization and COVID-19 vaccine resistance in the US. Prog. Mol. Biol. Transl. Sci. 188 , 81–100 (2022).

Link-Gelles, R. et al. Early estimates of bivalent mRNA booster dose vaccine effectiveness in preventing symptomatic SARS-CoV-2 infection attributable to Omicron BA. 5–and XBB/XBB. 1.5-related sublineages among immunocompetent adults—Increasing Community Access to Testing Program, United States, December 2022–January 2023. Morb. Mortal. Wkly. Rep. 72 , 119 (2023).

Article   CAS   Google Scholar  

Dyer, O. Covid-19: Florida’s surgeon general used “careless” research practice in recommending against vaccination, his university finds. BMJ 380 , 110 (2023).

Lazarus, J. V. et al. A global survey of potential acceptance of a COVID-19 vaccine. Nat. Med. 27 , 225–228 (2021).

Lazarus, J. V. et al. COVID-SCORE: A global survey to assess public perceptions of government responses to COVID-19 (COVID-SCORE-10). PLoS One 15 , e0240011 (2020).

Ye, Y. et al. Equitable access to COVID-19 vaccines makes a life-saving difference to all countries. Nat. Hum. Behav. 6 , 207–216 (2022).

Anderson, T. & Shattuck, J. Design-based research: A decade of progress in education research?. Educ. Res. 41 , 16–25 (2012).

Notarte, K. I. et al. Impact of COVID-19 vaccination on the risk of developing long-COVID and on existing long-COVID symptoms: A systematic review. eClinicalMedicine 53 , 101624 (2022).

Brodin, P. et al. Studying severe long COVID to understand post-infectious disorders beyond COVID-19. Nat. Med. 28 , 879–882 (2022).

Couzin-Frankel, J. & Vogel, G. Vaccines may cause rare, long covid-like symptoms. Science 375 , 364–366 (2022).

Download references

Acknowledgements

Dr. Kevin Moore, Dr. Anne Waswa, Dr. James Drimalla, and Alexandra Yon contributed to the creation and iterative improvement of the RRT. Ximeng Huang improved the graphic design of RRT. Dr. Katelyn Jetalina (Your Local Epidemiologist) contributed to improving the RRT by reviewing data related to immune compromised populations. Various experts on mathematical and statistical thinking provided feedback on RRT including Dr. Neil Hatfield, Dr. Amy Hackenberg, Dr. Leslie Steffe, Dr. Pat Thompson, Dr. Steven Boyce, and Dr. Halil Tasova. Evan Fimbres edited the manuscript. We disclose support for the research of this work from the National Science Foundation [DUE- 2032688] and University of Georgia Internal Research Grant.

Author information

Authors and affiliations.

Department of Mathematics, Science, and Social Studies Education, University of Georgia, Athens, 30606, USA

Cameron O’Neill Byerley, Dru Horne, Mina Gong & Heather Lavender

Department of Mathematics and Statistics, Cal Poly Pomona, Pomona, 91768, USA

Stacy Musgrave & Hyunkyoung Yoon

Department of Dermatology, University of Washington, Seattle, 98195, USA

Laura A. Valaas

Department of Mathematical Sciences, University of Arkansas, Fayetteville, 72701, USA

Brian Rickard

Department of Information Studies, University of Wisconsin-Milwaukee, Milwaukee, 53201, USA

Min Sook Park & Sukjin You

Department of Mathematics, University of Arizona, Tucson, 85721, USA

Alison Mirin

Yavapai Elementary School, Scottsdale, 85257, USA

Surani Joshua

You can also search for this author in PubMed   Google Scholar

Contributions

C.B., M.G., D.H., S.M., L.V., B.R., A.M., and H.Y. contributed to writing, editing, and paper conceptualization. C.B., H.Y., S.J. M.P., S.Y., H.L., L.V., S.M. contributed to conceptualization, design, and iterative improvement of the RRT through qualitative research. L.V. (who is an MD and mathematics major) checked writing and RRT for medical accuracy. B.R., M.G., C.B. and D.H conducted statistical analysis. M.P., H.Y., M.G, C.B., S.J., and S.M. created and conducted the survey. H.Y., C.B., and S.J. secured NSF funding for creation of the RRT. S.Y. programmed the RRT. All authors approved the submitted version of this manuscript.

Corresponding author

Correspondence to Cameron O’Neill Byerley .

Ethics declarations

Competing interests.

The authors declare no competing interests.

Additional information

Publisher's note.

Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Supplementary Information

Supplementary information., rights and permissions.

Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/ .

Reprints and permissions

About this article

Cite this article.

Byerley, C.O., Horne, D., Gong, M. et al. An effective COVID-19 vaccine hesitancy intervention focused on the relative risks of vaccination and infection. Sci Rep 14 , 7419 (2024). https://doi.org/10.1038/s41598-024-57841-1

Download citation

Received : 12 June 2023

Accepted : 22 March 2024

Published : 28 March 2024

DOI : https://doi.org/10.1038/s41598-024-57841-1

Share this article

Anyone you share the following link with will be able to read this content:

Sorry, a shareable link is not currently available for this article.

Provided by the Springer Nature SharedIt content-sharing initiative

By submitting a comment you agree to abide by our Terms and Community Guidelines . If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate.

Quick links

• Explore articles by subject
• Guide to authors
• Editorial policies

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Do you need a spring COVID-19 vaccine? Research backs extra round for high-risk groups

Recent studies suggest staying up-to-date on covid shots helps protect high-risk groups from severe illness.

Social Sharing

New guidelines suggest certain high-risk groups could benefit from having another dose of a COVID-19 vaccine this spring — and more frequent shots in general — while the broader population could be entering once-a-year territory, much like an annual flu shot.

Medical experts told CBC News that falling behind on the latest shots can come with health risks, particularly for individuals who are older or immunocompromised.

"Even when the risk of infection starts to increase, the vaccines still do a really good job at decreasing risk of severe disease," said McMaster University researcher and immunologist Matthew Miller.

Who needs another COVID shot?

Back in January, Canada's national vaccine advisory body set the stage for another round of spring vaccinations. In a statement , the National Advisory Committee on Immunization (NACI) stated that starting in spring 2024, individuals at an increased risk of severe COVID may get an extra dose of the latest XBB.1.5-based vaccines, which better protect against circulating virus variants.

That means:

• Adults aged 65 and up.
• Adult residents of long-term care homes and other congregate living settings for seniors.
• Anyone six months of age or older who is moderately to severely immunocompromised.

The various spring recommendations don't focus on pregnancy, despite research showing clear links between a COVID infection while pregnant, and increased health risks. However, federal guidance does note that getting vaccinated during pregnancy can protect against serious outcomes.

"Vaccinated people can also pass antibodies to their baby through the placenta and through breastmilk," that guidance states .

What do the provinces now recommend?

Multiple provinces have started rolling out their own regional guidance based on those early recommendations — with a focus on allowing similar high-risk groups to get another round of vaccinations.

B.C. is set to announce guidance on spring COVID vaccines in early April, officials told CBC News, and those recommendations are expected to align with NACI's guidance. 

In Manitoba , high-risk individuals are already eligible for another dose, provided it's been at least three months since their latest COVID vaccine.

• Older P.E.I. residents, others at risk, urged to get spring COVID vaccine booster
• High-risk groups can now book spring COVID-19 vaccination in Nova Scotia

Meanwhile Ontario's latest guidance , released on March 21, stresses that high-risk individuals may get an extra dose during a vaccine campaign set to run between April and June. Eligibility will involve waiting six months after someone's last dose or COVID infection.

Having a spring dose "is particularly important for individuals at increased risk of severe illness from COVID-19 who did not receive a dose during the Fall 2023 program," the guidance notes. 

And in Nova Scotia , the spring campaign will run from March 25 to May 31, also allowing high-risk individuals to get another dose.

Specific eligibility criteria vary slightly from province-to-province, so Canadians should check with their primary care provider, pharmacist or local public health team for exact guidelines in each area.

Age still best determines when to get COVID vaccines, new research suggests

Why do the guidelines focus so much on age.

The rationale behind the latest spring guidelines, Miller said, is that someone's age remains one of the greatest risk factors associated with severe COVID outcomes, including hospitalization, intensive care admission and death. 

"So that risk starts to shoot up at about 50, but really takes off in individuals over the age of 75," he noted.

Canadian data suggests the overwhelming majority of COVID deaths have been among older adults, with nearly 60 per cent of deaths among those aged 80 or older, and roughly 20 per cent among those aged 70 to 79.

People with compromised immune systems or serious medical conditions are also more vulnerable, Miller added.

Will people always need regular COVID shots?

While the general population may not require shots as frequently as higher-risk groups, Miller said it's unlikely there will be recommendations any time soon to have a COVID shot less than once a year, given ongoing uncertainty about COVID's trajectory.

"Going forward, I suspect for pragmatic reasons, [COVID vaccinations] will dovetail with seasonal flu vaccine campaigns, just because it makes the implementation much more straightforward," Miller said.

• Just 15% of Canadians got updated COVID vaccines this fall, new figures show
• Spring COVID-19 vaccines available April 2 in N.B. for those at high-risk

"And although we haven't seen really strong seasonal trends with SARS-CoV-2 now, I suspect we'll get to a place where it's more seasonal than it has been."

In the meantime, the guidance around COVID shots remains simple at its core: Whenever you're eligible to get another dose — whether that's once or twice a year — you might as well do it.

What does research say?

One analysis, published in early March in the medical journal Lancet Infectious Diseases , studied more than 27,000 U.S. patients who tested positive for SARS-CoV-2, the virus behind COVID, between September and December 2023. 

The team found individuals who had an updated vaccine reduced their risk of severe illness by close to a third — and the difference was more noticeable in older and immunocompromised individuals.

Another American research team from Stanford University recently shared the results from a modelling simulation looking at the ideal frequency for COVID vaccines. 

• Elderly Canadians remain at higher risk of serious COVID from first infections, study suggests
• Spring vaccine dose suggested to protect seniors in Canada from severe COVID

The study in Nature Communications suggests that for individuals aged 75 and up, having an annual COVID shot could reduce severe infections from an estimated 1,400 cases per 100,000 people to around 1,200 cases — while bumping to twice a year could cut those cases even further, down to 1,000.

For younger, healthier populations, however, the benefit of regular shots against severe illness was more modest.

The outcome wasn't a surprise to Stanford researcher Dr. Nathan Lo, an infectious diseases specialist, since old age has consistently been a risk factor for severe COVID.

"It's almost the same pattern that's been present the entire pandemic," he said. "And I think that's quite striking."

More frequent vaccination won't prevent all serious infections, he added, or perhaps even a majority of those infections, which highlights the need for ongoing mitigation efforts.

ABOUT THE AUTHOR

Senior Health & Medical Reporter

Lauren Pelley covers health and medical science for CBC News, including the global spread of infectious diseases, Canadian health policy, pandemic preparedness, and the crucial intersection between human health and climate change. Two-time RNAO Media Award winner for in-depth health reporting in 2020 and 2022. Contact her at: [email protected]

• @LaurenPelley

Add some “good” to your morning and evening.

A vital dose of the week's news in health and medicine, from CBC Health. Delivered to your inbox every Saturday morning.

News & Media

• News Releases
• In The News
• Organization News
• Social Media
• Duke Health Blog

Public had Limited Understanding of Why a COVID-19 Vaccine was Paused

DURHAM, N.C. – Public health guidance about the pause in administering the Johnson & Johnson COVID-19 vaccine in April 2021 was difficult for many people to understand, according to a  study led by a Duke Health researcher. 

The findings of the study, appearing online April 1 in the Journal of Medical Internet Research, highlight the importance of clear public health guidance that builds trust within communities. 

“The pause of the Johnson & Johnson vaccine was an uncertainty-inducing incident in an already uncertainty-ridden time,” said lead author Vishala Mishra, a fellow in the  Department of Biostatistics and Bioinformatics at  Duke University School of Medicine . “One of the best ways to improve future communication efforts is to study the successes and failures of past ones.”

Researchers conducted an online rapid response survey about the CDC’s messaging around the temporary halt of the vaccine, which occurred after it had received authorization for public use. The CDC and FDA recommended the pause due to six reports of cerebral venous sinus thrombosis (CVST) in recently vaccinated people. CVST occurs when a blood clot forms in the brain and can lead to swelling or a hemorrhage.

For this study, 557 unvaccinated adults were separated into two groups, with group A comprised of people who specifically expressed neutral or negative sentiments about COVID-19 vaccines and group B comprised of people who had no expressed opinion about COVID-19 vaccines.

Survey results show that many respondents greatly overestimated the number of CVST reports that prompted the pause. When asked to guess a specific number, nearly 70% of respondents in group A and nearly 47% of respondents in group B estimated 100 or more cases. 

A majority of people also expressed reduced confidence in the safety of the Johnson & Johnson vaccine, but reported no change in their confidence of the safety of COVID-19 vaccines in general or intention to receive competing vaccines. 

Researchers said verbal descriptors can be misinterpreted so it is important to use numbers to limit risk perception and promote informed decision making. 

“We found significant negative associations between understanding of key information and vaccine hesitancy, suggesting that CDC crisis messaging may have been least accessible to people at the greatest risk of infection” Mishra said. 

“However, it was not all doom and gloom,” she said. “Our survey found that overall vaccine hesitancy remained stable following the J&J pause and it did not affect the public’s hesitancy about other mRNA vaccines.”

To improve public health guidance, the researchers said it’s important to recognize that communication and verbal descriptors can be nuanced and misinterpreted. They also encourage academics and science communicators to be more transparent about the limits of human knowledge by using numbers to communicate uncertainty.  

Additional authors include Joseph Dexter. The study received funding support from the Poynter Institute.

REVIEW article

The effect of covid-19 vaccine to the omicron variant in children and adolescents: a systematic review and meta-analysis.

• 1 Department of Outpatient, West China Hospital, Sichuan University, Chengdu, China
• 2 Department of Obstetrics and Gynecology, Peking University Third Hospital, Beijing, Beijing Municipality, China
• 3 National Clinical Research Center for Obstetrics and Gynecology, Peking University Third Hospital, Beijing, China
• 4 General Practice Ward/International Medical Center Ward, General Practice Medical Center, West China Hospital, Sichuan University, Chengdu, China
• 5 Department of Pediatrics, West China Second University Hospital, Sichuan University, Chengdu, Sichuan Province, China
• 6 Key Laboratory of Obstetric, Gynecologic and Pediatric Diseases and Birth Defects of Ministry of Education, West China Second University Hospital, Sichuan University, Chengdu, Sichuan Province, China

The final, formatted version of the article will be published soon.

Select one of your emails

You have multiple emails registered with Frontiers:

Notify me on publication

Please enter your email address:

If you already have an account, please login

You don't have a Frontiers account ? You can register here

Background: Omicron (B.1.1.529), a variant of SARS-CoV-2, has emerged as a dominant strain in COVID-19 pandemic. This development has raised concerns about the effectiveness of vaccination to Omicron, particularly in the context of children and adolescents. Our study evaluated the efficacy of different COVID-19 vaccination regimens in children and adolescents during the Omicron epidemic phase. Methods: We searched PubMed, Cochrane, Web of Science, and Embase electronic databases for studies published through March 2023 on the association between COVID-19 vaccination and vaccine effectiveness (VE) against SARS-CoV-2 infection in children and adolescents at the Omicron variant period. The effectiveness outcomes included mild COVID-19 and severe COVID-19. This study followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines and was prospectively registered in PROSPERO (CRD42023390481). Results: A total of 33 studies involving 16,532,536 children were included in the analysis. First, in children and adolescents aged 0-19 years, the overall VE of the COVID-19 vaccine is 45% (95% confidence interval [CI]: 40% to 50%). Subgroup analysis of VE during Omicron epidemic phase for different dosage regimens demonstrated that the VE was 50% (95% CI: 44% to 55%) for the 2-dose vaccination and 61% (95% CI: 45% to 73%) for the booster vaccination. Upon further analysis of different effectiveness outcomes during the 2-dose vaccination showed that the VE was 41% (95% CI: 35% to 47%) against mild COVID-19 and 71% (95% CI: 60% to 79%) against severe COVID-19. In addition, VE exhibited a gradual decrease over time, with the significant decline in the efficacy of Omicron for infection before and after 90 days following the 2-dose vaccination, registering 54% (95% CI: 48% to 59%) and 34% (95% CI: 21% to 56%), respectively. Conclusions: During the Omicron variant epidemic, the vaccine provided protection against SARS-CoV-2 infection in children and adolescents aged 0-19 years. Two doses of vaccination can provide effective protection severe COVID-19, with booster vaccination additionally enhancing VE.

Keywords: SARS-COV-2 variants, omicron, COVID-19 vaccines, Child, Adolescent

Received: 14 Nov 2023; Accepted: 27 Mar 2024.

Copyright: © 2024 Lu, Zeng, Yao, Luo and Ruan. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY) . The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

* Correspondence: Tiechao Ruan, Department of Pediatrics, West China Second University Hospital, Sichuan University, Chengdu, 610041, Sichuan Province, China

Disclaimer: All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article or claim that may be made by its manufacturer is not guaranteed or endorsed by the publisher.