COVID-19 Resource Center

COVID-19 Resource Center


FDA News.

Disclosures: Del Rio reports being an investigator on Moderna and Novavax COVID-19 vaccine studies. Lyke and Marrazzo report no relevant financial disclosures.
October 20, 2021
2 min read

FDA authorizes ‘mix and match’ booster doses for COVID-19 vaccines


FDA News.

Disclosures: Del Rio reports being an investigator on Moderna and Novavax COVID-19 vaccine studies. Lyke and Marrazzo report no relevant financial disclosures.
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The FDA on Wednesday said it is OK for Americans to choose a different COVID-19 vaccine for their booster shot.

The agency authorized the so-called “mix and match” strategy for boosting COVID-19 vaccines at the same time it amended emergency use authorizations to allow booster doses of the Moderna and Johnson & Johnson vaccines.

COVID vaccine stock image
Source: Adobe Stock.

The authorizations followed a 2-day meeting last week by the FDA’s Vaccines and Related Biological Products Advisory Committee (VRBPAC), which unanimously recommended that the agency authorize half-dose boosters of the Moderna vaccine for people aged 65 years or older and younger people with health and occupational risk factors, to be given after at least 6 months, and a booster shot at 2 months for anyone aged 18 years or older who received the Johnson & Johnson vaccine. The amended EUAs issued Wednesday aligned with those recommendations.

Near the end of the 2-day meeting last week, the VRBPAC heard Kirsten E. Lyke, MD, an associate professor of medicine at the University of Maryland, present data from an NIH study on the mixing and matching of COVID-19 booster doses.

Lyke reported that, among 458 participants, people who received a booster dose of a vaccine different than the vaccine they received for their primary series experienced protection that was similar to or greater than people who received the same vaccine as a booster, “meaning that the heterologous had as good or higher neutralizing antibodies following the boost” as homologous vaccination, Lyke said.

Evidence from the study also suggested that people who initially received the one-dose Johnson & Johnson vaccine were better off receiving one of the messenger RNA vaccines made by Moderna and Pfizer-BioNTech as their booster.

Carlos del Rio

“Personally, if I had received Johnson & Johnson, I would get a booster with an mRNA vaccine, because, from the from the mix-and-match study, the immunogenicity looks really fantastic,” Infectious Disease News Editorial Board Member Carlos del Rio, MD, told Healio.

The FDA authorized mixing vaccines without a recommendation by the VRBPAC, which only discussed — but did not vote on — the approach. Infectious Disease News Editorial Board Member Jeanne M. Marrazzo, MD, MPH, called the authorization “an important advance.”

Jeanne M. Marrazzo

“For one, it gives us flexibility depending on what vaccine is available and what our patients prefer,” Marrazzo, who directs the division of infectious diseases at the University of Alabama at Birmingham School of Medicine, told Healio. “For another, it acknowledges data that suggest a higher level of antibody response to an mRNA vaccine given after a first dose.”

The FDA had already authorized booster doses for Pfizer-BioNTech’s mRNA COVID-19 vaccine last month.

The CDC’s Advisory Committee on Immunization Practices will meet on Thursday to vote on recommendations for Moderna and Johnson & Johnson vaccine boosters.

Experts have suggested that patients may be confused about which vaccine they are supposed to receive as a booster, and when. Del Rio said it is important to remind patients about the good news from the NIH study — “that there's good reactogenicity and immunogenicity of mixing and matching our vaccines.”

“I think it is actually a really good idea, and I'm glad the FDA [approved] it because the reality is that this is how we're going to be looking at some of those vaccines, right?” del Rio said. “Let's suppose you're getting your influenza shot, and you say, ‘Well, I always get the GlaxoSmithKline flu vaccine, so I can't take the Sanofi flu vaccine.’ We take the vaccine that is there.”


Atmar RL, et al. medRxiv. 2021;doi:10.1101/2021.10.10.21264827.

FDA. Coronavirus update: FDA takes additional actions on the use of a booster dose for COVID-19 vaccines. Accessed Oct. 20, 2021.