Johnson & Johnson said a booster dose of its Covid-19 vaccine administered two months after the first shot increased protection against symptomatic illness in trial participants, as federal regulators evaluate data for the country’s strategy for rolling out boosters.
Data released Tuesday from a late-stage clinical trial showed that study participants in 10 countries including the U.S. who received a second dose of the company’s vaccine two months after the first had 75% protection against symptomatic Covid-19. Participants in the U.S. had 94% protection against the illness. J&J didn’t explain the reason for the difference in efficacy rates.
