A second dose of Johnson and Johnson’s coronavirus vaccine appears to increase protection from moderate to severe COVID-19, the company said Tuesday after months of questions on how well the efficacy of its single-shot regimen would hold up over time.
Summary results from an international Phase 3 trial run by J&J showed an additional shot, given eight weeks after the first, resulted in an estimated 75% protection against moderate to severe COVID-19, compared to placebo. Looking only at study participants in the U.S., J&J reported a higher efficacy estimate of 94%, but that figure was based on far fewer cases than the overall rate.
