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HomeInternationalJ&J vaccine recipients may need boosters against Delta variant

J&J vaccine recipients may need boosters against Delta variant

The Johnson & Johnson COVID-19 vaccine is substantially less effective against the Delta and Lambda variants than against the original virus and booster shots may be necessary, according to a new US study, reports The New York Times.

The study has not yet been peer reviewed but has been hailed as “particularly credible” because it was published by a team with no ties to any of the vaccine manufacturers.

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

Although troubling, the most recent findings result from laboratory experiments conducted with blood samples and may not reflect the vaccine’s performance in the real world. But the conclusions add to evidence that those 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 J&J earlier this month suggesting that a single dose of the vaccine is effective against the variant even eight months after inoculation.

The new study is consistent with observations that a single dose of the AstraZeneca vaccine — which has a similar architecture to the J&J vaccine — shows only about 33% efficacy against symptomatic disease caused by 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 Nathaniel Landau, a virologist at New York University’s Grossman School of Medicine, who led the study.

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.

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. He said the new study was particularly credible because it was published by a team with no ties to any of the vaccine manufacturers.

The Delta variant is the most contagious version yet of the coronavirus. It accounts for 83% of infections in the United States, Dr Rochelle Walensky, director of the US Centers for Disease Control and Prevention, said at a Senate hearing on Tuesday. Delta may cause more breakthrough infections than earlier forms of the virus, but more than 99% of the hospitalisations and deaths are occurring among unvaccinated people.

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.

But evidence on the J&J vaccine has been limited, because it was rolled out later than the mRNA vaccines, writes The New York Times. Most studies of effectiveness of the coronavirus vaccines were conducted at medical centers and hospitals that relied on samples from staff members who received the mRNA vaccines.

The J&J vaccine has also been dogged by reports of blood clots and a rare neurological syndrome, as well as problems with contamination at a US manufacturing plant.

Landau’s team would probably have seen a similar increase in the vaccine’s potency if they had looked at the data over time, said Dr Dan Barouch, a virologist at Beth Israel Deaconess Medical Center in Boston. The data on the J&J vaccine’s strength against the Delta variant at Day 29 is not much different from those reported in his own study, Barouch said.

“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.

Landau and his colleagues looked at blood samples taken from 17 people who had been immunised with two doses of an mRNA vaccine and 10 people with one dose of the J&J vaccine. 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,” 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.

The US Food and Drug Administration has said “Americans who have been fully vaccinated do not need a booster shot at this time,” and the agency is unlikely to change its recommendations based on laboratory studies. But the new data should prompt the F.D.A. to revisit its recommendations, Landau said: “I hope that they read our paper and think about it.”


Study details

Comparison of Neutralizing Antibody Titers Elicited by mRNA and Adenoviral Vector Vaccine against SARS-CoV-2 Variants

Authors: Takuya Tada, Hao Zhou, Marie I Samanovic, View ORCID ProfileBelinda M. Dcosta, Amber Cornelius, Mark J. Mulligan, Nathaniel R. Landau



The increasing prevalence of SARS-CoV-2 variants has raised concerns regarding possible decreases in vaccine efficacy. Here, neutralizing antibody titers elicited by mRNA-based and an adenoviral vector-based vaccine against variant pseudotyped viruses were compared. BNT162b2 and mRNA-1273-elicited antibodies showed modest neutralization resistance against Beta, Delta, Delta plus and Lambda variants whereas Ad26.COV2.S-elicited antibodies from a significant fraction of vaccinated individuals were of low neutralizing titer (IC50 <50). The data underscore the importance of surveillance for breakthrough infections that result in severe COVID-19 and suggest the benefit of a second immunization following Ad26.COV2.S to increase protection against the variants.


Full NYT story: J&J vaccine may be less effective against Delta, study suggests (Open access)


Full Comparison of Neutralizing Antibody Titers Elicited by mRNA and Adenoviral Vector Vaccine against SARS-CoV-2 Variants study (Open access)

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