J.&J. Vaccine May Be Less Effective Against Delta, Study Suggests

The coronavirus vaccine made by Johnson & Johnson is much less effective against the Delta and Lambda variants than against the original virus, according to a new study posted online on Tuesday. Although troubling, the findings result from experiments conducted with blood samples in a laboratory, and may not reflect the vaccine’s performance in the real world. But the conclusions add to evidence that the 13 million people inoculated with the J.&J. vaccine may need to receive a second dose — ideally of one of the mRNA vaccines made by Pfizer-BioNTech or Moderna, the authors said. The conclusions are at odds with those from smaller studies published by Johnson & Johnson earlier this month suggesting that a single dose of the vaccine is effective against the variant even eight months after inoculation.