A person receives a dose of Pfizer BioNTech’s vaccine for coronavirus disease (COVID-19) at a mobile vaccination site in the Bronx, New York, on August 18, 2021.
David ‘Dee’ Delgado | Reuters
Food and Drug Administration officials on Wednesday declined to take a stance on whether Pfizer should support booster shots of the Covid-19 vaccine, saying U.S. regulators had not reviewed all of the available data.
“There are many potentially relevant studies, but the FDA has not independently reviewed or verified the underlying data or its conclusions,” they wrote in a 23-page document posted on the agency’s website. “Some of these studies, including data from the vaccination program in Israel, will be summarized during the VRBPAC meeting on September 17, 2021.”
Staff said that some observational studies suggest that the Pfizer vaccine may become less effective over time against symptomatic infections or against the Delta variant, while others do not.
“Overall, the data suggests that COVID-19 vaccines currently licensed or approved in the United States still provide protection from severe COVID-19 illness and death in the United States,” they wrote.
The data the FDA is studying includes efficacy numbers from Israel, where researchers there have published observational studies showing that the Pfizer vaccine’s effectiveness against infections has waned over time.
In separate documents released on Wednesday, Pfizer argued that a third dose of the Covid vaccine restored infection protection to 95% six months after a second vaccination.
FDA staff seemed skeptical of the data, as observational studies do not meet the same standards as formal clinical studies.
“It should be recognized that while observational studies can provide an understanding of effectiveness in practice, there are known and unknown biases that can affect their reliability,” the agency said. “In addition, post-approval US-based studies of the efficacy of BNT162b2 may most accurately show the vaccine’s effectiveness in the US population.”
The staff report is intended to inform the FDA’s Advisory Committee on Vaccines and Related Biological Products, which will meet on Friday to review Pfizer’s application for approval of Covid booster doses for the general public. The published documents give an insight into the agency’s perspective on third shots.
The Biden government has announced that it will offer booster injections to the public as early as next week pending FDA approval. The move is part of President Joe Biden’s broader plan to confront a higher number of Covid cases fueled by the rapidly spreading Delta variant.
Scientists and other health experts have repeatedly criticized the plan, saying the data cited by federal health officials are non-compulsory and describe government pressure on boosters as premature.
There is currently no consensus in the biomedical community on boosters for the general public, said Dan Barouch, an immunologist at Harvard Medical School.
“There are high-level experts who fall on different sides of the debate,” he said. “Right now it will be interesting to see where the debate goes, but apparently what is known is that the Biden government has suggested that boosters are needed.”
The Biden government has cited three studies published by the Centers for Disease Control and Prevention which showed that vaccines protection against Covid had deteriorated over several months. The government’s plan, outlined by senior health officials, is for people to receive a third dose eight months after the second shot of the Pfizer or Moderna vaccine. Biden said scientists were looking to move the third shot up by three months.
When the government announced the plan in August, senior health officials said they fear protection from serious illnesses, hospitalizations and deaths could “wear off” in the coming months, especially for those at higher risk or during the earlier stages the vaccination were vaccinated roll out.
A group of scientists, including two senior FDA officials and the World Health Organization, published an article Monday in The Lancet magazine arguing that no booster vaccination is currently required for the general public. While the Covid vaccine’s effectiveness against minor illnesses may decline over time, protection against serious illnesses appears to persist, the scientists said.
On Tuesday, WHO officials again urged rich nations to stop distributing Covid vaccine booster doses in hopes of providing more vaccinations to poorer countries with delayed vaccination rates.
“There are countries with less than 2% vaccination coverage, most of them in Africa, that do not even get their first and second dose,” said Director General Tedros Adhanom Ghebreyesus at a press conference. “And it’s really not right to start with boosters, especially giving healthy populations.”
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