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Should You Get an Additional COVID-19 Bivalent Booster?


An additional bivalent booster offers extra protection for those at high risk of COVID-19-related hospitalization and death.

[Originally published: April 21, 2023. Updated: May 17, 2023.]

Note: The Johnson & Johnson (Janssen) COVID-19 vaccine is no longer available in the U.S. In May 2023, existing doses of the J&J vaccine expired and the Centers for Disease Control & Prevention (CDC) directed providers to dispose of any that had gone unused.

Information in this article was accurate at the time of original publication. Because information about COVID-19 changes rapidly, we encourage you to visit the websites of the Centers for Disease Control & Prevention (CDC), World Health Organization (WHO), and your state and local government for the latest information.

The number of cases of COVID-19 may be dropping, but the disease is still a concern for those who are 65 and older (more than 53 million people in the United States) and those with weak immune systems (about 7 million people). Those two groups are more likely than others to get severely ill or die from COVID-19—that’s why the U.S. Food and Drug Administration (FDA) and Centers for Disease Control and Prevention (CDC) are offering a second bivalent booster shot.

This booster is identical to the reformulated, or "bivalent," booster introduced in fall 2022 in that it targets two virus strains: Omicron subvariants BA.4 and BA.5 and the original SARS-CoV-2 virus. The bivalent boosters are available from both Pfizer-BioNTech and Moderna.

“I support the booster for those who are eligible and want to get it,” says Yale Medicine infectious diseases specialist Scott Roberts, MD.

Studies have shown that COVID-19 vaccines can prevent COVID-related hospitalization and death. What’s more, the vast majority of the more than 1.1 million deaths from COVID-19 in the U.S. have been in people 50 and older, and the numbers increase with age, according to CDC data. Still, only 42.4% of people 65 and older—and 16.7% of all eligible people in the U.S.—have gotten the first bivalent shot, according to the CDC. “I consider that number to be quite poor,” Dr. Roberts says.

As part of a bigger plan, the FDA also announced that the current bivalent mRNA vaccines will replace the original monovalent Moderna and Pfizer-BioNTech mRNA COVID-19 vaccines, which target the original, or ancestral, SARS-CoV-2 virus strain; they are no longer authorized for use in the U.S.

The agency is also planning to further simplify future COVID-19 vaccinations by offering a reformulated booster for a vastly expanded age group in the fall, around the same time as the flu shot becomes available. That booster will be based on recommendations about current circulating SARS-CoV-2 virus strains.

Below, Dr. Roberts answered common questions about the FDA's decision to offer an additional COVID-19 booster to certain groups.

1. Should you get an additional COVID-19 booster? ­­­

It depends. The CDC recommends that everyone 6 years of age and older receive an updated (bivalent) mRNA COVID-19 vaccine, regardless of whether they previously completed their (monovalent) primary series. But if you’re age 6 and older and have already received an updated mRNA vaccine, you don’t need to take any action unless you are 65 and older or immunocompromised.

If you are 65 and older, you are eligible for an additional bivalent booster if you had your primary COVID-19 vaccine and are at least four months out from a previous bivalent booster shot.

You are also eligible for an additional booster two months out from your last shot if you are moderately or severely immunocompromised, meaning you’re an organ transplant recipient, you receive immunosuppressive medications or treatments (such as chemotherapy), you’re on certain medications that weaken your immune system over time (such as corticosteroids), or you have a weakened immune system due to a medical condition (such as cancer).

You can self-attest to your immunocompromised status, which means you do not need documentation to get any COVID-19 vaccine doses you are eligible to receive, according to the CDC.

The FDA also allows additional doses for immunocompromised people “at the discretion of, and at intervals determined by, their health care provider.”

2. Why is an additional dose of the bivalent vaccine allowed only for certain groups?

Older or immunocompromised people are more vulnerable to severe disease, hospitalization, and death from COVID-19. That vulnerability is a growing concern as the bivalent boosters first offered last fall are already showing a decline in effectiveness.

In April, a study published in the New England Journal of Medicine showed that the bivalent booster offered last fall provided added protection against severe illness and death from COVID-19, but it waned over time. It also showed older adults and those who are immunocompromised to be much more vulnerable to hospitalization and death from COVID-19 than young, healthy people.

Another consideration is that older people’s bodies mount a less robust immune response to COVID-19, even if they are vaccinated. “This is true with many types of vaccines, and it's also true of viruses, such as respiratory syncytial virus infection [RSV] and influenza,” Dr. Roberts says. “It makes age one of the greatest risk factors for a negative outcome, in terms of infectious diseases, such as COVID.”

3. How do these changes to COVID vaccination affect children?

Because the monovalent (original) mRNA COVID-19 vaccines are no longer authorized for use in the U.S., unvaccinated children 6 months through 4 years of age may receive a three-dose primary series of the Pfizer-BioNTech bivalent vaccine. Those who are unvaccinated and 6 months through 5 years of age may get a two-dose primary series of the Moderna bivalent vaccine.

Children in the above-mentioned age groups who have already received one, two, or three doses of a monovalent COVID-19 vaccine may get a bivalent shot, but the number of doses they receive will depend on the type of vaccine (Moderna or Pfizer) they’ve already received, their age, and vaccination history.

4. What if you’ve never been vaccinated against COVID-19?

Most unvaccinated people are eligible for a single dose of a bivalent COVID vaccine, rather than multiple primary doses of the original monovalent mRNA vaccines.

5. What if you were vaccinated with the Novavax or Johnson & Johnson vaccine?

For the majority of people, the CDC recommends the Pfizer-BioNTech, Moderna, or Novavax boosters (and vaccines) over the Johnson & Johnson vaccine. This is because the Johnson & Johnson vaccine has been associated with a rare but serious blood clotting disorder.

However, the Johnson & Johnson booster may be used in the following circumstances:

  • For people 18 and over who had a severe reaction to a Pfizer or Moderna vaccine
  • For those who would otherwise remain unvaccinated due to limited accessibility of Pfizer, Moderna, or Novavax boosters
  • For those who prefer the Johnson & Johnson vaccine despite safety concerns.

The Novavax vaccine is available in limited situations as a booster to people 18 and older. The CDC says people may get a Novavax booster if they cannot or do not want to receive a Pfizer or Moderna bivalent booster, they completed their primary vaccine series at least 6 months previously, and they have not received another booster dose.

6. How is this COVID booster different from the previous one?

It’s not. These boosters are the same as the bivalent boosters first offered last fall. As with the previous boosters, these are mRNA vaccines, offered by Pfizer-BioNTech and Moderna, that target two virus strains: the original SARS-CoV-2 and Omicron subvariants BA.4 and BA.5.

7. Will this shot protect against the current Omicron strain, XBB.1.5?

Neither the 2022 bivalent booster nor this one is specifically formulated to protect against Omicron XBB.1.5, which in mid-April was the virus strain responsible for more than 88% of COVID-19 cases in the U.S. “However, that doesn’t mean this booster won’t protect against XBB.1.5 or other new Omicron variants that may arise,” Dr. Roberts says.

XBB.1.5 is still an Omicron offshoot, and we know the bivalent booster has been effective against Omicron subvariants, Dr. Roberts explains. A CDC study in January assessed the bivalent vaccine introduced last fall for its effectiveness against Omicron subvariants XBB and XBB.1.5 in people who had previously received two to four monovalent vaccine doses. Scientists found that the updated booster’s real-world effectiveness against symptomatic infection for the first three months after vaccination for those strains was similar to what it was against BA.5.

“If you have some immunity to a variant and are exposed to a new offshoot of it, you’ll have some protection,” Dr. Roberts says.

8. Why is the additional bivalent booster allowed but not ‘recommended’ for immunocompromised people or those 65 and older?

“The CDC is giving people the option,” says Dr. Roberts. Although he is recommending the vaccine to eligible patients, some have given the authorization of a second bivalent booster mixed reviews.

For example, some experts challenging the additional booster have brought up what’s called “immune imprinting,” a theory that says if you keep boosting against older COVID variants, you could be turning your immune response’s focus to the older variants no longer circulating. Then, future boosters that target newer variants may not generate as robust a response for you, Dr. Roberts explains. “However, that’s a hypothetical area of concern, and we haven't seen it play out yet in the data,” Dr. Roberts says.

“Most data supports the boosters as being effective,” he says. “They do a good job of boosting the immune response against the current variants.”

9. Where can I get the COVID-19 bivalent booster?

As with previous COVID-19 vaccines, this booster will be available at participating pharmacies and provider offices. To find a location near you that carries the vaccine and to schedule an appointment, go to You can also call 1-800-232-0233 (TTY 1-888-720-7489).

Information provided in Yale Medicine articles is for general informational purposes only. No content in the articles should ever be used as a substitute for medical advice from your doctor or other qualified clinician. Always seek the individual advice of your health care provider with any questions you have regarding a medical condition.