New York – A new study, published without peer review in bioRxiv, shows that the Johnson & Johnson vaccine is much less effective than its Moderna or Pfizer at protecting against the COVID-19 Delta variant, the most contagious variant yet that is now responsible for 83 percent. It said that both mRNA vaccines were significantly better at neutralizing Delta than J&J’s Janssen vaccine—unfortunate news for the roughly 13 million people in the US who have received the single-dose shot. The Food and Drug Administration says: “Americans who have been fully vaccinated do not need a booster shot at this time,” according to The New York Times. But Nathaniel Landau, a virologist at NYU’s Grossman School of Medicine, thinks that the new data should be enough for the FDA to reconsider. He told The Times, “I hope that they read our paper and think about it.” Existing studies show the J&J shot may be more effective as a two-dose vaccine.