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FDA Greenlights ‘Mixing and Matching’ COVID-19 Vaccine Boosters

three vaccine syrignes

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Key Takeaways

  • The FDA has authorized use of the Moderna, Pfizer, and Johnson & Johnson COVID-19 booster dose.
  • The FDA says people do not have to get a booster dose of the same brand of vaccine they originally received.


The Food and Drug Administration (FDA) in October 2021 gave its OK for eligible individuals who received the Moderna or Johnson & Johnson COVID-19 vaccines to get booster doses. (A booster for Pfizer vaccine recipients was previously authorized.)

Significantly, however, the booster doses do not have to be the same brand as the original vaccine a person received. In a statement released late in the day on Wednesday, the agency said “today, the FDA is also authorizing the use of heterologous (or ‘mix and match’) booster dose[s] for currently available (i.e., FDA-authorized or approved) COVID-19 vaccines.” 

In a call with reporters on Wednesday evening following the authorization of the boosters, Peter Marks, MD, PhD,  director of the FDA’s Center for Biologics Evaluation and Research, said the authorization of the mix and match boosters was based on  clinical trial data from the National Institute of Allergy and Infectious Diseases, discussion about that data by the FDA’s Vaccines and Related Biological Products Advisory Committee last week, and the agency’s own evaluation of the available data.  

The Case for Mixing and Matching 

The studies on the mix and match boosters, not yet peer reviewed, found a strong immune response from any booster dose. For people who originally got the Johnson & Johnson vaccine, a booster dose with Pfizer or Moderna produced a more robust antibody response than a booster with Johnson & Johnson. For that reason, the Centers for Disease Control and Prevention (CDC) have preferred Pfizer or Moderna vaccine boosters over Johnson & Johnson’s booster.

Based on those studies and the committee and agency discussions, the FDA said in its statement that “a single booster dose of any of the available COVID-19 vaccines may be administered as a heterologous [mix and match] booster dose following completion of primary vaccination with a different available COVID-19 vaccine.” 

For People Who Originally Received Johnson & Johnson 

According to the FDA, Johnson & Johnson COVID-19 vaccine recipients 18 years of age and older (the current starting age for booster doses) can receive a single booster dose of the J&J vaccine, the Moderna vaccine (with the half dose that has been authorized as the booster dose) or the Pfizer vaccine (full dose) at least two months after receiving their J&J primary vaccination.  

For People Who Originally Received Pfizer or Moderna

The agency said that Moderna and Pfizer vaccine recipients who qualify for boosters can get a booster dose of the Moderna, Pfizer, or J&J vaccine at least five months after completing their primary vaccination.

Acknowledging that both patients and doctors will have questions about the authorized boosters, the FDA updated the fact sheets for each vaccine to include the booster dose information. 

CDC Sign-off Follows

The FDA’s decision on booster doses, while important, was actually an interim step. The next day, an advisory committee to the Centers for Disease Control and Prevention (CDC) also met to discuss booster doses, ultimately agreeing with the FDA’s recommendation.

The CDC director reviews the ACIP committee’s recommendations but can modify them. For example, the ACIP committee did not recommend that Pfizer boosters be given to people whose jobs put them at higher risk of contracting COVID. But CDC director Rochelle Walensky, MD, MPH, allowed it.


During a call with reporters following the FDA’s authorization of the boosters on Wednesday acting FDA commissioner Janet Woodcock MD, said the agency “expects many people to get the  same series they received, but individuals are advised to speak to providers if they have concerns.” 

Checking with a provider is important, said Woodcock, “because some people don’t know what vaccine they got or had a reaction [to the vaccine they got], so they want another brand.” 

Peter Marks of the FDA said during the reporter call that he thought ultimately, if COVID vaccines continue to be necessary, people may just get boosters without knowing what brand it is, “much as they often do when it comes to the flu shot.” 

Aaron Glatt, MD, chief of infectious diseases at Mount Sinai South Nassau in New York and a spokesperson for the Infectious Disease Society of America, tells Verywell that he thinks, “once it is clear that all of [the COVID vaccines] work equally well, it may come to that.” But Glatt says ‘it’s very difficult to make any prediction on this right now. It will tremendously depend upon whether any more resistant COVID-19 strains develop and or whether side effects are noted in one vaccine more than another.” 

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.

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  1. Centers for Disease Control and Prevention. COVID-19 vaccine booster shots.