Research on Covid Booster Shots is Conflicting

Two examples of new research published this week suggested the booster shots were not necessary.,


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The F.D.A.’s day of lively debate revealed key new questions about the evidence on boosters.

Mark Turney, 66, a kidney transplant patient, received a booster shot of the Pfizer-BioNTech Covid-19 vaccine in Hartford, Conn., last month. Scientists are debating the need for a third shot.
Mark Turney, 66, a kidney transplant patient, received a booster shot of the Pfizer-BioNTech Covid-19 vaccine in Hartford, Conn., last month. Scientists are debating the need for a third shot.Credit…Joseph Prezioso/Agence France-Presse — Getty Images
  • Sept. 17, 2021Updated 4:34 p.m. ET

Advisers to the Food and Drug Administration on Friday questioned an assertion by researchers in Israel and by the drug company Pfizer that the protection from its coronavirus vaccines wanes over time not just against infection, but against severe illness and hospitalization.

The advisers were meeting officially to evaluate the application for booster doses of Pfizer-BioNTech vaccine, and they ended up voting to recommend authorizing booster shots for those who are 65 or older or are at high risk of severe Covid-19, after overwhelmingly voting against recommending them broadly for those over 16.

Among the details that surfaced during the lively debate: Israel defines anyone with an accelerated respiratory rate and an oxygen level of below 94 percent as being severely ill. By contrast, the Centers for Disease Control and Prevention considers people who are sick enough to be hospitalized as having severe disease, according to Dr. Sara Oliver, a C.D.C. scientist who presented data on the trajectory of the pandemic in the United States.

The discrepancy might explain why the two countries have reported vastly different outcomes in people who are fully immunized. Israeli researchers said they have seen large numbers of hospitalized patients who had received two doses months earlier, but in the United States, the C.D.C. has reported that vaccinated patients make up about 2 percent of people hospitalized for Covid-19.

Other advisers noted that antibodies are expected to wane over time, but studies so far — including from Pfizer — have indicated that immune cells, which would prevent severe illness, remain stable. One study published this week showed steady levels of immune cells seven months after the second dose.

Some advisers seemed more inclined to OK the booster shots, noting that the boosters appear to have eased Israel’s surge.

Three other important pieces of research landed just this week. On Monday, in the journal The Lancet, an international team of scientists analyzed dozens of studies and concluded that boosters are not yet needed by the general population, and that the world would be better served by using vaccine doses to protect the billions of people who remain unvaccinated.

Two of the authors are vaccine experts at the F.D.A. itself, and both had already announced plans to resign over what they felt was undue pressure from the Biden administration to clear booster shots.

On Wednesday, scientists at the agency posted an assessment online hinting that they, too, are unconvinced that there’s enough evidence that boosters are needed. “Overall, data indicate that currently U.S.-licensed or authorized Covid-19 vaccines still afford protection against severe Covid-19 disease and death in the United States,” according to their executive summary.

But some F.D.A. leaders had publicly endorsed booster shots. “The need for an additional dose at six months to provide longer term protection should not come as a surprise, as it’s likely necessary for the generation of a mature for immune response,” Dr. Peter Marks, one of the agency’s top officials, said in the meeting on Friday.

White House officials have said they are particularly worried by data from Israel, where officials have said that vaccinated people are seeing waning immune responses and higher rates of infection. Alarmed by the rise in cases, Israeli officials offered third doses of the vaccine to everyone older than 12.

Researchers from Israel published early results from that rollout on Wednesday in the New England Journal of Medicine — but few outside scientists found the findings convincing.

The team collected data on the effects of booster shots from the health records of more than 1.1 million people over age 60. At least 12 days after the booster, rates of infection were elevenfold lower — and rates of severe disease nearly twentyfold lower — in those who received a booster compared with those who had received only two doses, the researchers found.

The results are unsurprising, experts said, and do not indicate long-term benefit.


Dr. Celine Gounder, an infectious disease expert at Bellevue Hospital in New York and a former member of the Biden-Harris Covid-19 advisory council.Credit…Amr Alfiky/The New York Times

“We have known for some time that the vaccines elicit less robust immune responses in the elderly,” said Dr. Celine Gounder, an infectious disease specialist at Bellevue Hospital Center and a former adviser to the Biden administration. “Recommending additional doses of vaccine for the elderly isn’t controversial.”

Vaccination remains powerfully protective against severe illness and hospitalization in the vast majority of people in all of the studies published so far, experts said. But the vaccines do seem less potent against infections in people of all ages, particularly those exposed to the highly contagious Delta variant.

The cumulative data so far suggest that only older adults might need boosters — and maybe not even them. But White House officials had said that they did not want to wait for hospitalizations to begin rising — if they ever do — among the vaccinated before taking action.

The Biden administration has said that booster doses could be rolled out quickly if they were deemed necessary.

British scientists have recommended giving third doses to adults over 50 and other medically vulnerable people. France, Germany, Denmark and Spain are also considering boosters for older adults or have already begun administering them. Israel is already contemplating fourth doses for its population.

But recent history leaves many experts leery of adding the United States to the list.

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