A booster shot of the Johnson & Johnson vaccine generates a ninefold increase in COVID-19 antibodies compared with a single dose of the vaccine, the company announced Wednesday. It’s promising news, but too soon to tell what this means for the battle against the Delta variant.
In two not-yet-peer-reviewed studies, researchers found that 17 participants who were given a second jab after six months had antibody levels that were nine times higher than they were a month after the first dose. That increase was seen in trial participants aged 18 to 55, and in people over 65 who received a lower booster dose, according to the drugmaker’s press release. The findings have been submitted to the medical preprint MedRxiv.
The new data comes with caveats: Neither of the studies looked at real-world efficacy; they were based on two phase two clinical trials, which are smaller than the phase three trials designed to show the efficacy of a vaccine. The phase three data, with as many as 30,000 participants, have not yet been made public.
In its press release, Johnson & Johnson said that it was already in talks with the Food and Drug Administration and the Centers for Disease Control and Prevention, as well as the European Medicines Agency, regarding a possible booster. “We look forward to discussing with public health officials a potential strategy for our Johnson & Johnson COVID-19 vaccine, boosting eight months or longer after the primary single-dose vaccination,” Mathai Mammen, head of research at Johnson & Johnson, said in a statement.
The announcement comes just a week after the federal government announced that it’s gearing up to offer a booster shot for those who received an mRNA vaccine from Pfizer or Moderna beginning the week of September 20. The 14 million people who received the single-shot Johnson & Johnson vaccine were not part of the Biden administration’s initial booster plan due to lack of data.