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By ZEKE MILLER
WASHINGTON (AP) —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 cam- paign 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 rec- ommend 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 sim- pler for Americans and allow people who may have had adverse reactions to the ini- tial dose to try a different shot.
Last week, the U.S. said it would recognize combinations of vaccines adminis- tered overseas for the purposes of entering the country. The practice was com- mon in Canada and some European countries in the early months of the vaccina- tion campaign.