Second J&J Dose Needed for Delta Variant

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Johnson & Johnson’s COVID vaccine is much less effective against the Delta and Lambda variants than against the original wild-type virus, according to a new study posted on the BioRxiv preprint server on Tuesday.

Though a cause for concern, the results come from in vitro tests, and may not reflect the real world vaccine performance. However, the authors said this adds to evidence that the 13 million people inoculated with the J&J vaccine may need a second dose, preferably an mRNA vaccine, the authors said.
The findings, which are still to be peer reviewed, are however consistent with observations that a single dose of the AstraZeneca vaccine, which is similar to the J&J one, shows only about 33 percent efficacy against developing symptoms with the Delta variant.

“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,” said study leader Nathaniel Landau, a virologist at NYU’s Grossman School of Medicine.

Other experts said the results are what they would have expected, because all of the vaccines seem to work better when given in two doses. “I have always thought, and often said, that the  J&J vaccine is a two-dose vaccine,” said John Moore, a virologist at Weill Cornell Medicine in New York.

Dr Moore pointed to several studies in monkeys and people that have shown greater efficacy with two doses of the J&J vaccine, compared with one dose. The new study was particularly credible, he said, because it was published by a team not linked to any vaccine manufacturer.

But the data from the new study “do not speak to the full nature of immune protection,” said Seema Kumar, a spokeswoman for J&J. “Studies sponsored by the company indicate that the vaccine “generated strong, persistent activity against the rapidly spreading Delta variant,” she said.

The Delta variant is the most transmissible of the SARS-CoV-2 variants, and has become dominant in South Africa. 

Several studies have suggested that the mRNA vaccines made by Pfizer-BioNTech and Moderna will maintain their efficacy against the coronavirus, including all variants identified so far. One recent study showed, for example, that the vaccines trigger a persistent immune reaction in the body that may protect against the coronavirus for years. The J&J vaccine is newer, and has had fewer studies.

The J&J vaccine has had reports of rare blood clots and extremely rare neurological disorders, as well as problems with contamination at a US manufacturing plant. This is still not as bad as the disastrous news that the AstraZeneca vaccine was virtually ineffective against the Beta variant which was then the dominant strain in South Africa.

Small studies by J&J affiliated researchers suggested that the vaccine was only slightly less effective against the Delta variant than against the wild-type virus, and that antibodies stimulated by the vaccine grew in strength over eight months.

Dr Dan Barouch, a virologist at Beth Israel Deaconess Medical Center in Boston said it was important to consider the vaccine’s strength over time.

“Fundamentally I don’t see that there’s any discordance,” he said. “The question is that of kinetics, it’s not just magnitude, because immune responses are not static over time.” The new study also did not consider other components of immune defence, he added.

Dr Landau and his colleagues had compared blood samples taken from 17 people who had two doses of an mRNA vaccine and 10 who had one J&J vaccine dose.

The  J&J vaccine started out with a lower efficacy than the mRNA vaccines and showed a bigger drop in efficacy against the Delta and Lambda variants. “The lower baseline means that what’s left to counter Delta is very weak,” Dr Moore said. “That is a substantial concern.”

Very few vaccines are given as a single dose, because the second dose is needed to amp up antibody levels, noted Akiko Iwasaki, an immunologist at Yale University. People who were inoculated with the J&J vaccine “are relying on that primary response to maintain high levels of antibodies, which is difficult, especially against the variants,” she said.

Boosting immunity with a second dose should raise the antibody levels high enough to counter the variants, she said.

Source: New York Times

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