An FDA committee is reviewing Moderna’s coronavirus vaccine. Here’s what to look for.

The FDA, in a report Tuesday, confirmed that in Moderna’s clinical trial, the two-shot regimen was 94 percent effective at preventing illness and was particularly effective against severe disease. The vaccine has not caused major safety problems, the report confirmed.

But other issues will get a close look from the 22-member panel, which includes experts on infectious diseases, epidemiology and immunology from throughout the country. Those topics include side effects, such as fatigue, headaches, muscle aches and pain at the injection site, which are not considered serious but can be extremely uncomfortable. These reactions were widespread but typically didn’t last long, according to the FDA and Moderna.

There also is certain to be a discussion about the potential for severe allergic reactions. A health-care worker in Alaska had a serious allergic reaction after getting the Pfizer-BioNTech vaccine, state officials revealed Wednesday. The Alaska case echoes two similar episodes in the United Kingdom in which health-care workers had serious but nonfatal allergic reactions to the vaccine. But the British workers had histories of severe allergic reactions, while the Alaska woman had none, officials said.

The first presentation is expected to be from FDA vaccine expert Doran L. Fink, who will explain what is required for an emergency use authorization. Such an authorization is a kind of temporary approval that can be used by the agency during public health emergencies. It requires less data than a full approval and can be granted more quickly. On vaccines, FDA officials say they are adhering mostly — but not entirely — to the criteria for a full approval.

Moderna officials, including Tal Zaks, the company’s chief medical officer and head of clinical development, will present data from a late-stage trial to make the case the vaccine should be authorized.

In that trial, 30,000 people were randomly assigned to receive either two shots of a vaccine given four weeks apart, or two saline shots. Investigators then waited as people were exposed to coronavirus in their daily lives, to see if there were more infections in the group that did not receive the real vaccine. They counted cases starting two weeks after the second dose, to measure how well the vaccine protected participants after their immune system had mustered a full response.

The numbers were decisive: There were 196 coronavirus cases in the trial, with all but 11 in the group that received the placebo shots. There were 30 cases of severe covid-19 and one death from covid-19 in the trial, also all in the group that received the placebo.

Members of the general public will address the committee for an hour sometime about noon. Judging from last week’s meeting on Pfizer-BioNTech, the speakers will include those who are wildly enthusiastic about the vaccine and those who oppose clearing it on an expedited basis.

After a lunch break, FDA medical officer Rachel Zhang will explain the agency’s view of the vaccine and explain what advice the agency wants to get from the panel. Judging from last week’s meeting on the Pfizer-BioNTech product, the FDA will ask the panel to vote on whether the benefits of the Moderna vaccine outweigh the risks for people 18 and older. A yes vote is essentially a recommendation to authorize the vaccine.

Sometime after 3 p.m. or so, the committee begins discussing the vaccine, probably including modest side effects and potentially severe allergic reactions. The panel will then vote on the FDA question on benefits outweighing risks. The agency isn’t required to follow the panel’s advice but usually does. And given the overwhelming vote last Thursday in favor of the Pfizer-BioNTech vaccine, which is similar to the Moderna one, a positive outcome seems all but assured.

The meeting is supposed to be adjourned well before dinnertime, but the session could run late.

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