New study finds potential benefits in mixing and matching COVID booster shots

TAMPA, Fla. - Mixing and matching booster shots may give better protection against COVID-19, according to a new government-funded study published Wednesday.

The new study from the National Institutes of Health looked at the immune response in 458 fully vaccinated people with nine different booster combinations.

"It's actually a full-on series and then mix and match booster. They split them up into three groups and gave them to a booster from one of the three vaccines," said Dr. Michael Teng, a virologist with University of South Florida Health who looked at the study.

There were about 50 people in each of the nine groups, and volunteers were given an extra dose of their original vaccine or a different manufacturer’s vaccine booster shot. The study suggests switching up works just as well or better.

"So if you've got the J&J first and you give an mRNA vaccine, Moderna or Pfizer, you get a better response than you would have otherwise," Teng said of one of the results.

The study also shows a high immune response for people who got the Pfizer or Moderna shots and then boosted with Johnson & Johnson, and it suggests that people who got the Pfizer and Moderna series could switch between each other for a third dose to create higher antibodies. But there are limits to the study, including its size and racial demographics.

"I think this is the one thing that that when we look at studies from other countries, not every country is, you know, racially as diverse as ours," said Teng. "Genetics plays a role in your immune response, and we've known that for a while. So we need to have that also be part of the studies."

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Mixing and matching vaccine boosters is not currently FDA-approved, but Teng said the study shows promise for the future.

"Once all of these vaccines become fully approved on their own, then there will be opportunities to, you know, get a booster maybe that is not the same," said Teng.

An FDA advisory committee meets Thursday and Friday to talk about booster shots for Johnson & Johnson and Moderna vaccines only for people staying with the same shot, not mixing and matching. For now, Pfizer is the only maker authorized for boosters for people who got the Pfizer vaccine.