A new laboratory study suggests recipients of Johnson & Johnson’s coronavirus vaccine may need a second dose. Experts say: We’re not sure yet.
The study, which was posted by bioRxiv on Tuesday, found J&J’s vaccine to be less effective against the delta and lambda variants compared with the original virus. It suggests that a second dose, ideally of Pfizer or Moderna, might help increase protection.
The study has not yet been peer-reviewed or published, so experts say people who have received J&J’s shot shouldn’t worry about finding a second dose at the moment. More research and clinical studies are necessary to determine who needs booster shots and when they may need them.
Maryland’s Department of Health follows the policies of the Centers for Disease Control and Prevention and the Food and Drug Administration, which have not changed their guidance on the single-dose J&J vaccines.
The delta variant is now the most contagious form of the coronavirus, accounting for 83% of all new cases in the United States. Amid delta’s threat, climbing COVID cases and slowing vaccination rates, here’s what to know about the new research developments.
What are the study’s findings?
The study was conducted with blood samples in a laboratory at New York University, comparing the performance of Pfizer’s and Moderna’s mRNA vaccines and J&J’s adenoviral vaccine against different virus strains. It found that J&J’s vaccine did not perform as well against the delta and lambda variants of the coronavirus compared with the original form of the virus.
“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, a virus specialist at NYU’s medical school who led the study, told The New York Times.
The findings line up with studies concluding that a single dose of the AstraZeneca vaccine, which is similarly structured to the J&J vaccine, is 33% effective against symptomatic disease from the delta variant. But they contradict studies published by J&J earlier this month that say a single dose is effective against the variant eight months after immunization.
Since the study is based on findings from a lab, it may not accurately represent how the vaccine works in the real world. Amesh Adalja, an expert in infectious diseases at Johns Hopkins, said lab-based studies often don’t paint the full picture of immunity.
“It doesn’t account for, for example, T-cell immunity,” Adalja said, referring to cells that play an important role in immune response. “It’s often better answered by a real-world study looking at people that have gotten the Johnson & Johnson vaccine and looking to see what happens to them clinically.”
Matt Laurens, a vaccine researcher at the University of Maryland School of Medicine, agreed that clinical data is crucial to determine who may need booster shots. He noted that multiple studies in the U.S. are continuing to follow people who have been vaccinated.