The Food and Drug Administration will likely announce authorization for boosters for Moderna and Johnson & Johnson shots. This follows the approval for a third Pfizer vaccine dose for many Americans last month. A U.S. official with knowledge of the matter, who was not allowed to speak publicly before the announcement, previewed the move Tuesday.
FDA was expected say that the FDA would recommend using the same brand as a booster, especially in the case of Moderna and Pfizer mRNA vaccines that have been most effective against coronavirus. The agency was still finalizing guidance on the single-shot J&J vaccination.
A preliminary government study on different booster combinations showed that an additional dose of any type of booster boosts levels of virus-fighting antibody, regardless of brand. The most dramatic response was seen in J&J vaccine recipients who received a single dose. They saw a 76-fold increase and a 35-fold jump in antibody levels shortly after receiving either a Moderna booster or a Pfizer booster. This contrasts with the fourfold increase after a second J&J shot.
Moderna's recommended dose in combination with other brands is one confusing decision. Moderna applied to reduce the booster's dose by half, arguing that this is too much for people who have already received two full strength shots. The mix-and-match study did not use full-strength boosters and it is impossible to determine if a half dose of Moderna booster would cause as strong an effect in J&J patients.
Mixing and matching can make it easier for Americans to get a booster and give people who have experienced adverse reactions to the first dose the opportunity to try another shot.
The United States announced last week that it will recognize foreign vaccine combinations for entry into the country. This practice was widespread in Canada and other European countries during the initial months of the vaccination campaign.