Johnson & Johnson’s experimental one-shot COVID-19 vaccine generated a long-lasting immune response in an early safety study, providing a glimpse at how it will perform in the real world as the company inches closer to approaching U.S. regulators for clearance.
More than 90% of participants made immune proteins, called neutralizing antibodies, within 29 days after receiving the shot, according to the report, and participants formed the antibodies within 57 days. The immune response lasted for the full 71 days of the trial.
“Looking at the antibodies, there should be good hope and good reason that the vaccine will work,” in the company’s late-stage clinical trial that’s soon to report results, J&J Chief Scientific Officer Paul Stoffels said Tuesday in an interview.
The one-shot vaccine generates more neutralizing antibodies than a single dose of other front-runner COVID-19 vaccines, all of which are two-shot regimens. But when compared with two shots of these rivals, the response to J&J’s single shot is in the same range, Stoffels said.
Interim results from the phase 1/2 trial of participants ages 18 and older were published Wednesday in the New England Journal of Medicine. The data expanded on more limited findings J&J first published in September.
J&J’s progress is being closely watched by top infectious disease experts because its vaccine has the potential to become the first that can protect people after just one shot, making mass-vaccination campaigns much easier. The company expects to get definitive efficacy data from a final-stage study by early next month, potentially leading to regulatory authorization by March.
The U.S. has granted emergency-use authorizations to two vaccines, one developed by Pfizer Inc. and its partner BioNTech SE, and the other by Moderna Inc. Both employ a technology called messenger RNA that has never before been used in an approved product, and each showed more than 90% efficacy against COVID-19 symptoms.
Those results were better than expected. U.S. government officials had earlier said any vaccine with greater than 50% efficacy would be considered a success. Based on that guidance, J&J aimed for 60% effectiveness, Stoffels said, but “we hoped and we planned for 70%.”
Within weeks, J&J will learn how its vaccine performed in a late-stage trial of 45,000 volunteers. Stoffels now thinks it has the potential to be even higher than 70% effective, based on the early-stage findings and other factors.
When the antibody response to J&J’s shot is compared to others that have been through final stage trials “there’s a good reason to believe we can get into very high levels of efficacy,” Stoffels said. “Will it be north of 90%? I don’t know. The data will tell us.”