J&J vaccine much less effective against Delta, other variants: Study

A healthcare worker loads a syringe with the Johnson & Johnson Covid-19 vaccine.
A healthcare worker loads a syringe with the Johnson & Johnson Covid-19 vaccine. Photo credit Stephen Zenner/Getty Images

The COVID-19 vaccine developed by Johnson & Johnson is less effective against the Delta, Lambda, and other variants of the virus, according to an NYU study released Tuesday.

The potentially concerning findings are the result of lab experimentation and not real-world vaccine performance.

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However, the research suggests that roughly 13 million people who have received the adenoviral vector Johnson & Johnson vaccine may need a booster, potentially an mRNA booster like the Pfizer-BioNTech or Moderna shots.

“The message that we wanted to give was not that people shouldn’t get the J&J vaccine,” said NYU professor of microbiology Nathaniel Landau, who co-authored the study. “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.”

The new study has not yet been peer-reviewed and has not been published in a scholarly journal. The AstraZeneca vaccine, made using the same process as J&J, has only been partially effective in protecting people from the Delta variant, a separate study found.

Experts say the results are not out of the blue.

“I have always thought, and often said, that the J&J vaccine is a two-dose vaccine,” John Moore, a New York virologist, told the Times.

The Delta variant is highly contagious and more deadly than the original strain of the virus. The Centers for Disease Control and Prevention said Tuesday the variant is now responsible for an estimated 83 percent of cases in the U.S. At the beginning of July, the variant was responsible for only about half of COVID-19 patients.