SAN DIEGO — A new study released Tuesday suggests the COVID-19 vaccine made by Johnson & Johnson produces significantly weaker antibody defenses to the delta variant than the original strain.
However, medical experts say the results are far from proof that the one-dose vaccine is ineffective against the variant in the real world.
The study by a team at New York University prompted a flurry of concerned headlines Tuesday. The New York Times initially published a report titled, "One Dose of J.&J. Vaccine Is Ineffective Against Delta, Study Suggests."
The paper later changed the title to "J.&J. Vaccine May Be Less Effective Against Delta, Study Suggests."
The NYU scientists drew blood from 10 people who got the J&J vaccine and put their protective antibodies in a dish. Then, they introduced different COVID-19 variants to see how well the antibodies stopped them.
On average, the team found the Johnson & Johnson vaccine was about seven times weaker against the delta variant than the original strain of COVID-19. Those results were a more significant drop-off than those seen in people who received the Pfizer or Moderna vaccine.
The NYU study has not yet undergone peer review.
J&J is the only one-dose COVID-19 vaccine approved for emergency use in the U.S. The authors of the paper suggested that people who got the shot may benefit from a second dose.
However, outside experts like UC San Francisco's Dr. Peter Chin-Hong said it's too soon to make that assumption.
"You can't necessarily extrapolate laboratory-based studies to what happens in real life," he said.
That's because vaccines create more defenses than just antibodies. They also train living cells called "Killer T cells" and "Helper T cells." The three branches work together like branches of the military — the army, the navy and the air force.
"What we've known about J&J for a while is that the protection doesn't directly track with those antibody numbers," said Dr. Shane Crotty, a professor at the La Jolla Institute of Immunology.
During the company's clinical trials in South Africa, the Johnson & Johnson vaccine was 64% effective against the elusive variant there, now called the beta variant.
While the new NYU study did not measure T cell responses, it found the J&J antibodies perform about the same against delta as they do against beta — an encouraging clue, Crotty said.
The Johnson & Johnson vaccine "may lose a little more of its protection against just cases per se, but it'll still stay really highly protective against bad COVID, hospitalization level COVID," he said.
The one-dose J&J vaccine was authorized later than Pfizer's and Moderna's vaccines, so there have been fewer studies on it.
The NYU study conflicts with some of the earlier data. Experts say that could be because the team ran tests less than three months after the shot, on average.
Johnson & Johnson released research this month that found antibody levels grew in strength over eight months.
"Just like wine, it may get better with age," Chin-Hong said.
For now, experts say the bigger worry is about those who are still unvaccinated — people who have not gotten the shot account for 99% of the hospitalizations and deaths from the delta variant.
This story was originally published by Derek Staahl on Scripps station KGTV in San Diego.