As Pfizer's booster AdComm nears, FDA staffers say COVID vaccines are already working as intended

Ahead of the FDA's advisory meeting to review Pfizer's COVID-19 booster application, agency staffers voiced skepticism about the need to quickly roll out follow-up shots. As it stands, authorized vaccines are doing their job, the staffers said.

In briefing documents ahead of Friday's meeting, FDA reviewers said that while "some observational studies" suggest the efficacy of Pfizer two-dose vaccine wanes over time, overall data "indicate that currently US-licensed or authorized COVID-19 vaccines still afford protection against severe COVID-19 disease and death in the United States."

The FDA's Vaccines and Related Biological Products Advisory Committee plans to review the data Friday and make recommendations to the agency. The White House has said it plans to start giving COVID-19 booster doses during the week of Sept. 20, pending regulatory nods.

After the White House unveiled its booster plan last month, critics questioned the scientific evidence supporting the plan, and some said it's not ethical to give third doses to Americans while many people around the world have yet to get one dose. The World Health Organization called for a booster moratorium until the end of the year, but several countries are ignoring that plea.

Amid the debate, two FDA vaccine leaders—Marion Gruber, Ph.D., director of the FDA’s Office of Vaccines Research and review director, and Deputy Director Phillip Krause, M.D.—said they'd be leaving the agency this fall. They didn't indicate a reason for leaving, but in a paper published in The Lancet this week, Gruber, Krause and others said it's too soon to start giving boosters to the general public.

Current data supporting boosters are "preliminary and difficult to interpret," the authors wrote. Instead, those vaccines could provide more benefit in other countries.

“If unnecessary boosting causes significant adverse reactions, there could be implications for vaccine acceptance that go beyond COVID-19 vaccines,” the scientists wrote. The experts said boosting among the general public should only proceed if “there is clear evidence that it is appropriate.”

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For its part, Pfizer has spent months generating booster data and arguing that follow-up shots are appropriate to elicit the best possible protection. In its submission for the Friday meeting, the company said data from Israel and the U.S. show that protection wanes six to eight months after the second dose of Comirnaty, also known as BNT162b2.

"The totality of the available data supports the public heath need for a booster (third) dose of BNT162b2 at approximately six months after the second dose of BNT162b2 for individuals 16 years of age and older," the company said.

Pfizer and BioNTech's COVID-19 vaccine scored an FDA emergency use authorization in December and a full approval last month. Even if the FDA's independent vaccine advisors recommend a booster dose, the agency would still have to issue its own approval. And Centers for Disease Control and Prevention vaccine advisers have yet to issue clear backing for follow-up doses.

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Meanwhile, it appears the government will be unable to administer booster shots for the two-dose Moderna vaccine next week as originally hoped. The company only submitted its booster application in early September, so the regulatory review likely won't finish by next week.

And recipients of the Johnson & Johnson vaccine are still waiting to hear detailed guidance about booster plans for that vaccine. J&J touted booster data in late August and said it was working with regulatory authorities on the subject, but exact timelines for potential J&J booster shots remain unclear.