An FDA advisory panel knocked down Pfizer and BioNTech's pitch for COVID-19 booster shots for everyone but rebounded on the committee's follow-up allowance for third shots in the elderly and high-risk people.
The committee voted 16-2 to reject Pfizer’s bid for a full approval for boosters for people 16 and older.
“It may eventually be indicated for the general population,” committee member Ofer Levy, M.D., Ph.D., said. “I just don’t think we’re there yet in terms of the data.”
However, the FDA's Center for Biologics Evaluation and Research (CBER) vaccine advisory committee followed up with a unanimous recommendation for approval for the Comirnaty vaccine as a booster for people 65 and older, and people with high risk factors such as diabetes and obesity.
In a separate vote that was not part of the official recommendation, members unanimously agreed to include healthcare workers and others in higher risk occupations as eligible for boosters.
The FDA is expected to make its decision next week. If the recommendation is upheld, people who are eligible will be able to receive a booster dose six months after their second vaccine.
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In a statement provided after the committee's recommendation, Pfizer said it would continue to gather information to support its belief that there is a need for boosters.
"These data, and the larger body of scientific evidence presented at the meeting, underscore our belief that boosters will be a critical tool in the ongoing effort to control the spread of this virus,” said Kathrin Jansen, Ph.D., Pfizer's head of vaccine R&D. “We thank the committee for their thoughtful review of the data and will work with the FDA following today’s meeting to address the committee’s questions, as we continue to believe in the benefits of a booster dose for a broader population.”
Several committee members raised the issue of myocarditis, a severe heart condition that struck young, mostly male people after receiving a second vaccine dose. The booster data Pfizer presented Friday from a study done in Israel aren’t comprehensive enough to show whether booster doses would increase the risk. The study included only 329 participants.
“I have a very serious concern about myocarditis in young people,” said James Hildreth, M.D., Ph.D. “If it’s related to the immune response and the booster shots induce a very strong response, is that going to amplify the risk?”
Hildreth and Cody Meissner, M.D., also wondered whether boosters would be more effective if they matched the delta variant—a relatively easy tweak for mRNA technology, Hildreth said.
Another issue: In the absence of T- and B-cell counts, there still is uncertainty about how antibody levels relate to protection.
“Understanding the true correlates of protection and how that can inform durability assessments going forward still remains an open question,” said Michael Kurilla, M.D., Ph.D. “We really need to get a better handle on understanding exactly how these vaccines are mediating protection and the durability of that protection.”
Debate has been heated on the subject. Two FDA experts, who argued in a medical journal this week that there was no evidence to support offering boosters to the general populace, will leave the agency before the end of the year.
During Friday’s meeting, in an open public session, most participants urged the committee to recommend rejection of boosters or a delay to collect more evidence on their safety and effectiveness before approving them to the general public.
The lone committee members who voted for full approval of the vaccine as a booster were Jay Portnoy, M.D., and Mark Sawyer, M.D.
“It would be great to wait until we have all of the data about safety,” Portnoy said. “But my hospital is filling up with kids who have COVID. We didn’t want to rush in to approve the vaccine for them, and now, look where we are.”