Johnson & Johnson's COVID-19 vaccine may be much less effective against the delta and lambda variants of the virus compared to the original strain, according to a study posted July 20 on the preprint server bioRxiv.
The study — conducted by researchers from NYU Grossman School of Medicine in New York City who have no affiliation to any COVID-19 vaccine makers — used blood samples from 17 people vaccinated with two doses of an mRNA vaccine and 10 people vaccinated with one dose of Johnson & Johnson's shot.
Researchers found that Johnson & Johnson's COVID-19 shot was significantly less effective at producing neutralizing antibodies against the delta and lambda variants.
Johnson & Johnson's COVID-19 vaccine is less effective against the original COVID-19 strain compared to mRNA vaccines from Pfizer and Moderna, and "The lower baseline means that what's left to counter delta is very weak," John Moore, PhD, a virologist at Weill Cornell Medicine in New York, told The New York Times. "That is a substantial concern," he added.
Because the study was conducted using blood samples in a lab, the results may not reflect the shot's performance in the real world, the Times reported. It also didn't analyze other components of the body's immune defense besides antibody levels, and it hasn't been peer reviewed or published in a scientific journal.
The study suggests that the 13 million people in the U.S. who've been vaccinated with Johnson & Johnson's shot may need a booster dose of Pfizer or Moderna's vaccine to protect against virus variants.
"The message that we wanted to give was not that people shouldn't get the J&J vaccine, but we hope that in the future, it will be boosted with either another dose of J&J or a boost with Pfizer or Moderna," Nathaniel Landau, PhD, a virologist at NYU's Grossman School of Medicine, who led the study, told the Times.
Smaller studies sponsored by Johnson & Johnson suggested the shot is effective against the delta variant for at least eight months.
The delta variant now accounts for 83 percent of COVID-19 infections in the U.S. More than 99 percent of deaths from the variant are occurring in unvaccinated people, the Times reported.
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