Guidelines for approving a coronavirus vaccine will be the focus of FDA advisers meeting Thursday

The vaccine advisory committee, meeting remotely in an all-day session, is not reviewing a specific vaccine because no company has applied for the FDA’s imprimatur. Rather, the group is expected to debate the FDA’s standards governing whether a vaccine is sufficiently safe and effective to warrant an emergency use authorization. It will also weigh in on the conduct of clinical trials once a vaccine is cleared and monitoring safety on an ongoing basis.

During the morning session, officials from several government health agencies discussed the urgent need for vaccines, with the United States leading the world in covid-19 cases and deaths. They also talked about the federal decision to invest in scaling up half-a-dozen vaccines and about growing skepticism toward vaccines.

Marion Gruber, director of the FDA’s Office of Vaccines Research and Review, said the agency is moving as quickly — and carefully — as possible on vaccines. “Vaccine development can be expedited — however, I want to stress that it cannot and must not be rushed,” she said.

Later Thursday, the committee, at the request of the FDA, is expected to weigh in on topics including the effects of vaccines in specific populations and how to continue clinical trials after a vaccine is authorized. Should participants who received the placebo be notified and allowed to get the vaccine? If so, will that hurt the trial’s ability to collect useful data on an ongoing basis, and how can that be mitigated?

Even though the meeting does not deal with an individual vaccine, it is an important milestone, especially after protracted political melodrama involving the vaccine review process, experts said.

“The visual of scientists sitting around the table carefully discussing what a safe and effective vaccine might look like is an important moment for the FDA,” said Jason L. Schwartz, assistant professor of health policy and management at the Yale School of Public Health. “For months, all the FDA could do was offer promises about how science would guide its decisions on the vaccine. This shows how that will happen as data begins to come in.”

The first coronavirus vaccines are likely to be cleared by emergency use authorizations — which can be done much more quickly than full approvals and don’t require as much documentation. M. Miles Braun, former director of the FDA’s division of epidemiology and an adjunct professor at the Georgetown University School of Medicine, said during a media briefing Wednesday, that FDA officials will want to know from the committee that the agency is “on firm ground, and not missing any issues.”

The FDA has said it will hold additional advisory committee meetings to consider applications from vaccine makers, which could begin arriving as soon as mid-November.

The panel, called the Vaccines and Related Biological Products Advisory Committee, is made up mostly of academic experts in infectious diseases, immunology and biostatistics. Some members recused themselves because they work at hospitals where coronavirus vaccine trials are being conducted or are involved in the trials. They were replaced by temporary members, including Arnold Monto, a University of Michigan epidemiologist who will serve as committee chairman, according to documents on the FDA website.

The FDA has used advisory committees for decades to bulk up its expertise and win buy-in from the public and outside scientists on its decisions. The FDA is not required to take advice from the panels but often does. The vaccine committee is expected to play an especially important role given the political pressure exerted by the White House on the FDA in recent weeks and months.

The White House held up the guidance, but the FDA circumvented the blockade by publishing it as part of briefing materials provided to the advisory committee for Thursday’s meeting. The White House subsequently cleared the guidelines.

When Thursday’s committee meeting was announced by the FDA in August, some administration critics worried the scheduled date was further evidence the agency was being pressured to advance a vaccine before Election Day, said Rachel Sachs, a law professor at Washington University in St. Louis.

“There was a lot of suspicion that the timing was motivated by the political calendar,” she said. But she added that FDA Commissioner Stephen Hahn and the agency’s career scientists have in recent weeks “done an admirable job of putting some distance between the FDA and the White House.”

Drug companies, working closely with the U.S. government and fueled by an infusion of more than $10 billion in taxpayer money, have developed a half-dozen vaccine candidates. None has been proved safe and effective. Once a company has gathered what it considers compelling evidence, the FDA review is expected to take a few weeks.

Before authorizing a vaccine, regulators will require the shot to be at least 50 percent effective, that at least five people receiving the placebo develop severe cases of covid-19 and that there be at least two months of follow-up on half of the study participants.

Two of the leading candidates are being tested by pharmaceutical giant Pfizer and biotech company Moderna. Pfizer has projected having enough cases of covid-19 among study participants to assess the effectiveness of its vaccine in October and sufficient safety data to seek a regulatory okay by mid-November. Moderna will probably have 53 covid-19 cases among participants by November — enough for a first look at the data — with sufficient safety data reported just before Thanksgiving. Other vaccines are coming down the pipeline.