U.S. pharmaceutical company Johnson & Johnson announced Wednesday that clinical trials it has conducted show a second shot of the company’s COVID-19 vaccine produced an antibody response nine times higher than the original single dose.
In a news release, the company said it conducted two Phase 1/2a studies in individuals previously vaccinated with its single-shot vaccine. The interim data from those studies showed a booster dose of the vaccine generated “a rapid and robust increase in spike-binding antibodies, which bind to and neutralize an invading virus.”
The company said the boost in antibodies was “nine-fold higher than 28 days after the primary single-dose vaccination.” It said significant increases in binding antibody responses were observed in participants between the ages of 18 and 55, and in those 65 years and older, who received a lower booster dose.
“Phase 1/2a clinical trials are smaller than the Phase 3 trials designed to show the efficacy of a vaccine,” the company’s statement said. Johnson & Johnson is also studying a two-dose vaccine in as many as 30,000 people in a Phase 3 trial, the results of which have not yet been released.
Mathai Mammen, global head of research for Johnson & Johnson, said the company is submitting the results of its studies to the U.S. Food and Drug Administration (FDA), the U.S. Centers for Disease Control and Prevention (CDC), the European Medicines Agency (EMA) and other health authorities for potential use of the vaccine as a booster eight months or later after the primary single-dose vaccination.
The Johnson & Johnson Phase 1/2a studies have been submitted to the medRxiv online medical and health science archive and distribution server ahead of peer review.
Some information for this report was provided by Reuters.