US likely to OK mix-and-match booster shots
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 with authorization for boosters of the Moderna and Johnson & Johnson shots and follows approval 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 using the same brand for a booster was still preferable, especially for mRNA vaccines from Pfizer and Moderna deemed most effective. 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 singledose 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 four-fold 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.