Johnson and Johnson is touting the benefits of a booster dose for its single-shot vaccine.
The company revealed Wednesday that the extra shot of its COVID-19 vaccine resulted in antibody levels that were nine times higher compared with those who received the one dose.
The results were part of interim data from two early-stage trials. J&J says full results will be released in coming weeks.
Up until now there had been no evidence about the effect of a booster dose of the J&J vaccine.
Advisers for the U.S. Centers for Disease Control and Prevention had been waiting for word on how to advise immunocompromised individuals who received the J&J vaccine.
According to a press release from J&J, studies show significant increases in binding antibody responses, which means the body's white blood cells join in to fight off COVID-19, in participants aged 18-55.
Those 65 years and older also saw a meaningful response when given a lower booster dose.
J&J said it is working with the CDC, the U.S. Food and Drug Administration, the European Medicines Agency, the World Health Organization and other health authorities about delivering the J&J booster shot.
Despite the convenience of the one-dose vaccine, compared to two doses for Pfizer-BioNtech and Moderna, the J&J shot has had the lowest use rate in Europe of all the approved inoculations, and lags in the U.S. as well due to safety concerns and manufacturing stumbles.