Today, Johnson & Johnson (J&J) announced that a second dose of its COVID-19 vaccine given 2 months after the first raises its effectiveness against moderate to severe disease to 94% in the United States. The booster was also well tolerated, generating side effects similar to those observed after the first dose.
Promising data, but some experts want more
In a press release, the company said that its phase 3 US clinical trial data showed that a booster dose given at 56 days conferred 94% protection against moderate to severe disease in nearly 30,000 adult participants. The confidence interval (CI), however, was wide, at 58% to 100%, leaving doubt as to the precision of the finding.
J&J also said that antibody levels quadrupled when a booster dose was administered at 56 days, while they jumped 12-fold when the booster was given at 6 months. Median follow-up was 36 days. The data have not been peer-reviewed, but the company said it would submit them for publication soon.
“We now have generated evidence that a booster shot further increases protection against COVID-19 and is expected to extend the duration of protection significantly,” Paul Stoffels, MD, J&J chief scientific officer, said in the release.