Second dose of Johnson & Johnson vaccine increases protection against COVID-19, maker says

A second shot of the Johnson & Johnson vaccine boosts protection against symptomatic and severe COVID-19, the disease caused by the coronavirus, the drug company announced early Tuesday. Those booster shots also generated additional antibodies, molecules churned out by the immune system to help fight off infections.

Under the Food and Drug Administration’s emergency-use authorization, the Johnson & Johnson vaccine is given as a single dose, unlike the two shots required for full immunization with the Pfizer-BioNTech and Moderna mRNA vaccines.

Results published this summer indicate that the Johnson & Johnson vaccine generates lasting amounts of antibodies able to target delta and other variants of concern. In June and July, when delta was ascendant, the effectiveness of the one-shot vaccine was 78% against observed C-19, according to a report published Thursday that has not yet gone through peer review.

A second dose, given 56 days later, further improves protection, the company said in a news release Tuesday. According to the company’s Ensemble 2 study, a Phase 3 randomized clinical trial, efficacy was 100% against severe or critical COVID-19 for two weeks after the booster. Efficacy against symptomatic disease in the United States was 94%.

Full data from that trial was not released, the company said, and will be submitted for publication in months.

Antibody levels, too, spiked after booster shots. People who received a Johnson & Johnson booster shot two months after vaccination had antibody levels four to six times higher, while the levels in people who had boosters at six months eventually rose 12-fold, the company said.

Regulators would have to authorize Johnson & Johnson booster shots before the public could receive them. On Sunday, National Institute of Allergy and Infectious Diseases Director Anthony Fauci told NBC News that the FDA review of second Johnson & Johnson shots, as well as Moderna boosters, is “a couple to a few weeks away. . . . We’re working on that right now to get the data to the FDA, so they can examine it and make a determination about the boosters for those people.”

Because it does not require a second appointment, the Johnson & Johnson vaccine had been sent to harder-to-reach communities soon after the shot became available. Nearly 15 million Americans received Johnson & Johnson doses, while about 166 million people have been fully vaccinated with the vaccines made by Pfizer-BioNTech and Moderna.