Addressing the committee, Martha Dawson, the president of the National Black Nurses Association, said that some patients will feel more comfortable using protein-based vaccines, a technology that has been in use for decades. “I encourage the F.D.A. to give us another, more traditional medical intervention in this fight,” she said.

In clinical trials, the Novavax vaccine was found to have an efficacy of 90.4 percent at preventing mild, moderate or severe infection with older variants of the virus. None of the volunteers who got the vaccine experienced moderate or severe infection, translating to an efficacy of 100 percent.

The trial took place before the rise of the Delta and Omicron variants, which have evaded some of the immunity from other vaccines.

In briefing documents released on Friday, F.D.A. scientists identified six cases of myocarditis and pericarditis, forms of heart inflammation, in about 40,000 trial volunteers. The F.D.A. documents said that the cases raised concern that the vaccine was the cause and that the rates of the problems could turn out to be higher than with mRNA vaccines.

Moderna and Pfizer-BioNTech did not find any cases of myocarditis or pericarditis in their initial clinical trials. But after authorization, once the vaccines were given to millions of people, they were both found to create a small extra risk of myocarditis in boys and young men.

In their presentation on Tuesday, Novavax officials defended their vaccine against those concerns. Their analysis found that myocarditis and pericarditis cases were balanced across the group of volunteers that received the vaccine and the group that received a placebo. In the real world, there were reports of one case of likely myocarditis and eight cases of likely pericarditis out of 744,000 doses given in rich countries that have authorized the vaccine, the company said.

“We believe that the totality of the clinical evidence here is not enough to establish an overall causal relationship with the vaccine,” said Dr. Denny Kim, Novavax’s chief safety officer.