July 21, 2021
With the Delta variant now accounting for 83% of new COVID-19 cases in the U.S., a new study warns that the Johnson & Johnson vaccine might not offer as much protection against it as it does the original virus.
By studying blood samples, researchers found that not only did the J&J vaccine have overall lower efficacy compared with the Pfizer and Moderna vaccines, it was also very weak against the Delta variant. They say a second dose of the vaccine may be needed.
"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 booster with Pfizer or Moderna," Nathaniel Landau, a virologist at NYU's Grossman School of Medicine, told The New York Times.
These latest findings contradict the findings of smaller studies previously published by J&J that reported the vaccine offers protection against the variant for up to eight months, according to The Wall Street Journal.
The NYU study is published online on the preprint server BioRxiv and hasn't yet been peer-reviewed or published in a medical journal.
Because the study relied on laboratory testing, a J&J spokesperson told the New York Times that it doesn't reflect the vaccine's real-life performance against the variant.
For the study, Landau and his team analyzed blood samples from 17 people who had received two doses of an mRNA vaccine and 10 people who were immunized with a single dose of the J&J vaccine.
The idea that two doses of a COVID-19 vaccine is better than one is not new. A British study released back in May reported that a single dose of the AstraZeneca vaccine also wasn't as effective against the Delta variant as two doses. And even with double the vaccine, it was only 60% effective.
Other studies have also been exploring whether combining a dose of the J&J shot with a dose of an MRNA vaccine would be more effective than two doses of the J&J vaccine.