FDA panel debates boosters for Pfizer’s Covid vaccine

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Advisers to the US Food and Drug Administration have begun debating whether to recommend authorising Pfizer’s application to offer widespread booster doses of its Covid-19 vaccine.

Members of the regulator’s vaccine advisory committee are expected to vote at the end of Friday’s meeting on whether to endorse a third dose of the BioNTech/Pfizer vaccine. While the Biden administration has already announced plans to launch a booster programme next week, some health officials have pushed back.

Marion Gruber, the director of the FDA’s office of vaccine review, is one of two senior officials to have spoken out against the Biden administration’s booster plan, arguing that there is insufficient data to show that the effectiveness of two vaccine doses wanes over time. Gruber is retiring from the FDA next month, and allies have said she is unhappy at the way in which the regulator has been undermined by other parts of the Biden administration.

Speaking at the beginning of Friday’s meeting, Gruber stressed the high bar for recommending approval. “There’s an expectation that demonstration of the effectiveness of the additional dose is based on adequate and well-controlled clinical trials,” she said.

Pfizer told the committee boosters were needed to ensure the US does not experience a fresh wave of serious disease in coming months. Earlier this week, Pfizer and Moderna both released data suggesting the effectiveness of their mRNA vaccines can decline within months after a second shot.

As the FDA committee discussed the issue, the US Centers for Disease Control and Prevention released results from a study showing the efficacy of the Pfizer vaccine appeared to drop more steeply over time than jabs made by either Moderna or Johnson & Johnson.

The study, which analysed 3,689 people in 18 states over the summer, found Moderna’s vaccine was 93 per cent effective at stopping hospitalisation with Covid-19 for people with functioning immune systems in the first four months after the course had been completed, and 92 per cent effective after that. The BioNTech/Pfizer vaccine was 91 per cent effective in the first four months, but only 77 per cent effective after that.

“There is a clear erosion of vaccine protection over time against Covid-19, and emerging data indicates a loss of protection against hospitalisation,” William Gruber, senior vice-president of vaccine clinical R&D for Pfizer, told the committee, adding that “the time to restore protection with a safe and effective booster dose . . . is now”.

Sara Oliver, a scientist at the CDC’s division of viral diseases, noted that while protection against infection has decreased in recent months, “it is difficult to distinguish the effects of increased time since primary series versus the impact of the Delta variant.”

Data from Israel show severe Covid cases began to decline sharply about 10 days after the booster programme started. Covid cases there jumped more than 10-fold from early July to August, with 60 per cent of cases in fully vaccinated people, data from the country showed.

“If we had not started booster doses at the end of July we would have come to the capacity of the Israel hospitalisation capability and probably gone beyond it,” Sharon Elroy-Preiss, director of public health services at Israel’s health ministry, told the panel on Friday.

Pfizer is seeking to offer people aged 16 and older a booster of its two-dose messenger-RNA jab at least six months after receiving the second shot. US regulators could choose to limit the availability of booster doses to certain age groups.

Andy Slavitt, a former Covid adviser to US president Joe Biden, told the Financial Times: “The CDC may decide to say we recommend this for over-65s, but it is up to patients to discuss with their physicians whether to get a booster dose.”

If the committee recommends approving the application, the FDA is likely to give its final sign-off within days, and the CDC will issue guidelines for who should be eligible.

The FDA has already authorised booster shots of mRNA vaccines for people with weakened immune systems. But allowing booster shots more broadly is controversial, both because of the limited data available about the vaccines’ long-term effectiveness, and because many countries are still struggling to secure initial supplies.

Peter Marks, director of the FDA’s Center for Biologics Evaluation and Research, told the committee on Friday that it should focus “on the science related to the application under consideration today, and not on operational issues related to a booster campaign or on issues related to global vaccine equity”.

In a report published on Wednesday, FDA staff said the data were not conclusive on whether the vaccine’s ability to stop symptomatic infection declined significantly over time, a sign of internal frictions within the regulator about whether boosters are needed.

Others argue that US regulators should act quickly to stem the recent rise in coronavirus cases.

Ali Mokdad, professor of global health at University of Washington, said: “We need to get a booster for everyone and to move on. Once we have boosters out then we can donate vaccines.”

In an open letter published on Thursday ahead of the FDA meeting, Pfizer’s chief executive Albert Bourla said allowing people in rich countries to get boosters would not divert supplies from those in need: “If the data demonstrates their need, safety, and efficacy then they should be approved.”