麻豆传媒

An FDA advisory panel recommended emergency use authorization (EUA) of a booster dose of the Pfizer/BioNTech COVID-19 vaccine (Comirnaty) for individuals 65 and older, and those judged to be at high risk of severe COVID-19.

On Friday, the FDA's Vaccines and Related Biological Products Advisory Committee (VRBPAC) voted 18-0 that the known and potential benefits of a booster dose outweighed the known and potential risks for older adults, and for individuals 16 and up at high risk of severe disease.

The committee also agreed that healthcare workers and others at high risk for occupational exposure should be included in the EUA, which Peter Marks, MD, PhD, of FDA's Center for Biologics Evaluation and Research (CBER), said could include frontline workers, such as teachers, and certain infrastructure workers.

However, full approval of a booster dose was not recommended for all individuals ages 16 and older, by a vote of 2-16, with the committee mainly citing lack of safety data for the general population, including the risk for myocarditis in younger men.

Not only that, but VRBPAC did not buy manufacturer Pfizer's argument about "waning vaccine efficacy" as a significant driver of transmission, as CDC staff noted that transmission in the U.S. was mainly driven by the unvaccinated population.

"I have major concerns with regards to the extrapolation of the much older population to 16- and 17-year-olds," said Archana Chatterjee, MD, PhD, of Rosalind Franklin University in North Chicago. "There is no data on this population at all and the safety database presented was too small."

Pfizer presented safety and immunogenicity data from a cohort of about 300 adults ages 18 and older from the phase I/II/III trials who received booster doses, including only 12 adults ages 65 and older. This was the only data the committee was allowed to consider in its first voting question on approval, though Marks said committee members could consider the "totality of the evidence."

Committee members were most struck by real-world data from Israel, published this week in the (NEJM), that showed a benefit for a booster dose for adults ages 60 and older.

"The safety data we have reflects 60-year-olds," said Eric Rubin, MD, PhD, of Harvard T.H. Chan School of Public Health in Boston, and NEJM editor-in-chief. "That's quite different from 'people should get a third dose,'" which he described as "closer to being written as a mandate that everyone should get it."

Mark Sawyer, MD, of the University of California San Diego, was one of the only two "yes" votes on the first question, saying he thought approval for the general population was the "quickest, most efficient way for providers" to target certain high-risk populations who needed booster doses.

Sawyer also voted yes to the EUA question.

"I think this is a really amazing vote" for older adults and healthcare workers, who were vaccinated earlier and needed more protection, said Amanda Cohn, MD, of the CDC. She also said she was hopeful that once more data were available, they would reconvene to vote on a third dose for the general population.

Marks seemed to be leaning toward nudging the VRBPAC members to vote on the approval, taking time to show a slide from the CDC's Advisory Committee on Immunization Practices (ACIP) that showed that half of currently recommended vaccines require an additional dose 6 months after the primary series.

He added that the idea of preventing severe disease and hospitalization was only part of the job of a vaccine, as they are "indicated for various severities of disease prevention," including preventing continued spread of COVID-19 to vulnerable populations, such as children too young to be vaccinated.

Ultimately, the committee had no appetite for approval for a host of reasons. In addition to safety data, committee members said they wanted to see vaccines based on the circulating variant, studies of longer time between primary series and even a longer follow-up period following the booster dose to determine durability of immunity.

CDC staff also noted that they are currently evaluating data on the 1 million individuals who received a third dose of vaccine, and expect to make them available shortly.

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