Americans now have three options when choosing a COVID-19 booster shot, so who should consider swapping brands and who shouldn’t?

The Centers for Disease Control and Prevention (CDC) does not take a position on whether individuals should mix and match. The agency’s guidelines merely give people the option of using any approved or authorized vaccine, particularly if another brand is more convenient.

However, individuals first immunized with the single-shot Johnson and Johnson vaccine should probably switch to Pfizer or Moderna for their second dose, said UC San Francisco infectious disease specialist Dr. Peter Chin-Hong

“J&J was always number three in the medals count. They had lower protection from hospitalization. They had lower protection from symptomatic infection,” he said.

A small but influential study organized by the National Institutes of Health found J&J recipients produced significantly more antibodies when given an mRNA booster instead of a second dose of J&J.

The study examined every combination of the three vaccines with about 50 volunteers in each group. It found a Moderna booster elicited the largest immune response in J&J recipients, with a roughly 76-fold jump in antibodies compared to a four-fold increase from a second J&J shot. Pfizer produced a 36-fold increase.

However, there’s an important caveat to the study. The authors conducted their experiments with a 100-microgram dose of the Moderna vaccine, which is the standard dose for the first two shots. The actual authorized booster dose is only 50 micrograms.

The authors are now studying the impact of a 50-microgram dose of mRNA, but the smaller dose might narrow the gap between Modena and Pfizer. Pfizer uses a 30 microgram dose.

The bottom line for J&J recipients is that either mRNA vaccine is a good choice.

“I think most people would probably favor an mRNA vaccine after an initial J&J shot,” said Dr. Chin-Hong.

People who are prone to blood clots or heart problems and those undergoing cancer treatment should talk to their doctor about which shot is best.

Should Moderna or Pfizer recipients mix and match?

There are not many compelling reasons to switch from an mRNA vaccine to the J&J booster, except in cases where an individual had a rare allergic reaction to a vaccine ingredient, Dr. Chin-Hong said.

The NIH study showed a modest benefit of swapping one mRNA vaccine for another. Moderna recipients who crossed over to a Pfizer booster saw an 11.8-fold increase in antibodies compared to a 10.1-fold increase. Pfizer recipients who got a Moderna booster produced a 31.7-fold increase compared to 20.9-fold. (The Moderna booster was 100 micrograms, instead of 50.)

Those types of increases may make little real-world difference, experts said. Based on the results of other studies, the authors projected each of the aforementioned scenarios would result in protection of 90% or better.

“The difference between 20 times more and 30 times more is probably not significant from the body’s perspective. That’s just an amazing response, period,” said Dr. Chin-Hong. “At the end of the day, I think flexibility trumps everything. You can’t really go wrong by picking one or the other.”

Dr. Chin-Hong said your default choice should be the mRNA shot you previously got, but you might consider switching from team Moderna to a Pfizer booster if you’re particularly concerned about side effects.

The CDC released data Wednesday on about 275,000 booster doses through October 10. Those who got a Moderna booster reported higher rates of side effects like fatigue, muscle soreness, headache, and fever.

Still, both Pfizer and Moderna recipients generally reported fewer side effects after dose three than dose two.

This story was originally published by Derek Staahl at KGTV.

WASHINGTON —

Federal regulators are expected to authorize the mixing and matching of COVID-19 booster doses this week in an effort to provide flexibility as the campaign for extra shots expands.

The upcoming announcement by the Food and Drug Administration is likely to come along with authorization for boosters of the Moderna and Johnson & Johnson shots and follows the OK for a third dose for the Pfizer vaccine for many Americans last month. The move was previewed Tuesday by a U.S. health official familiar with the matter who was not authorized to speak publicly ahead of the announcement.

The FDA was expected to say that using the same brand for a booster was still preferable, especially for the mRNA vaccines from Pfizer and Moderna that have proved most effective against the coronavirus. The agency was still finalizing guidance for the single-shot J&J vaccine.

Preliminary results from a government study of different booster combinations found an extra dose of any type revs up levels of virus-fighting antibodies regardless of the brand people first received. But recipients of the single-dose J&J vaccination had the most dramatic response — a 76-fold and 35-fold jump in antibody levels, respectively, shortly after either a Moderna or Pfizer booster, compared to a four-fold rise after a second J&J shot.

One confusing decision is what Moderna dose to recommend in combination with other brands. Moderna has applied for its booster to be half the original dose, saying that’s plenty for people who already received two full-strength shots. But the mix-and-match study used full-strength extra doses, and there’s no way to know if a half-dose Moderna booster would trigger as strong a reaction in J&J recipients.

Allowing mixing and matching could make the task of getting a booster simpler for Americans and allow people who may have had adverse reactions to the initial dose to try a different shot.

Last week, the U.S. said it would recognize combinations of vaccines administered overseas for the purposes of entering the country. The practice was common in Canada and some European countries in the early months of the vaccination campaign.

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AP Medical Writer Lauran Neergaard contributed.