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The virus that causes COVID-19 has evolved. So has our protection: Bivalent vaccines from Pfizer and Moderna can help give your immune system a boost against the Omicron variant. That's why the U.S. Food and Drug Administration has authorized bivalent vaccines for people 6 months and older—including people who didn't get the original series of COVID-19 vaccines. Here's what to know.

Why do we need the updated boosters?

The virus that causes COVID-19 changes with time. Some newer variants spread more easily. And they are better at evading the current vaccines. According to the Centers for Disease Control and Prevention, the bivalent boosters offer protection from the original strain of the virus. But they also target the spike protein that helps the Omicron BA.4 and BA.5 variants infect cells. This is not unlike how experts update the flu shot each year to match the circulating strains.

Who can get them and when?

Most people who are 6 years old or older who haven't received a bivalent booster yet can get one dose of the updated vaccine. That's true whether or not they received the original vaccine series. Some people may be eligible for a second dose:

• People who are 65 or older can get a second dose four months or more after their first bivalent booster.
• People who have a weakened immune system should ask their doctors if they need a second dose of the bivalent vaccine.

Children ages 6 months through 5 years who have already had at least one dose of their primary vaccine series can get a bivalent booster. Ask your child's doctor how many doses they should receive.

Kids who haven't been vaccinated can get the bivalent vaccine too. According to FDA:

• 5-year-olds who have not been vaccinated for COVID-19 can get the bivalent vaccine as their primary series. The number of doses depends on the vaccine: Kids can get a single dose of the Pfizer vaccine or two doses of the Moderna vaccine.
• Children ages 6 months through 4 years who have not been vaccinated for COVID-19 can get the bivalent vaccine as their primary series. The number of shots depends on which vaccine they receive. For this age group, the Moderna vaccine is two doses, and the Pfizer vaccine is three doses.

Do I need this even if I'm already boosted?

If you got your booster before the change to the bivalent vaccine, you're eligible for the bivalent booster.

The updated shots should provide better protection from newer Omicron variants. It's also important to remember that vaccine immunity fades with time. Booster shots help to restore this protection.

What are the potential side effects from a booster shot?

The most common side effects are like those seen with primary series COVID-19 vaccines. They include pain at the injection site, fatigue, headache and fever. These side effects, if they happen, usually last a day or two.

Who might not be able to get a booster?

People who may have safety concerns about COVID-19 boosters include those who:

• Have had a serious reaction to a dose of COVID-19 vaccine or its ingredients.
• Have ever had a severe reaction to any vaccine.
• Have a moderate or severe acute illness.

You still may be able to get a booster shot in these situations. For instance, if you’re sick, you may have to wait a few days. Your doctor can advise you on the best course of action.

I’m not sure if a booster is right for me. How can I find out?

Talk to your doctor. They can help you understand the risks and benefits so you can decide what’s right for you.

Sources

• American Medical Association. "New Omicron boosters available from Pfizer and Moderna with Sandra Fryhofer, MD." https://www.ama-assn.org/delivering-care/public-health/new-omicron-boosters-available-pfizer-and-moderna-sandra-fryhofer-md.
• Centers for Disease Control and Prevention. "Stay Up to Date with COVID-19 Vaccines Including Boosters." https://www.cdc.gov/coronavirus/2019-ncov/vaccines/stay-up-to-date.html.
• Centers for Disease Control and Prevention. "https://www.cdc.gov/coronavirus/2019-ncov/vaccines/expect/after.html."
• Centers for Disease Control and Prevention. "Variants of the Virus." https://www.cdc.gov/coronavirus/2019-ncov/variants/index.html.
• U.S. Food and Drug Administration. "Coronavirus (COVID-19) Update: FDA Authorizes Changes to Simplify Use of Bivalent mRNA COVID-19 Vaccines." https://www.fda.gov/news-events/press-announcements/coronavirus-covid-19-update-fda-authorizes-changes-simplify-use-bivalent-mrna-covid-19-vaccines.
• U.S. Food and Drug Administration. "Coronavirus (COVID-19) Update: FDA Authorizes Moderna, Pfizer-BioNTech Bivalent COVID-19 Vaccines for Use as a Booster Dose." https://www.fda.gov/news-events/press-announcements/coronavirus-covid-19-update-fda-authorizes-moderna-pfizer-biontech-bivalent-covid-19-vaccines-use.