FDA Panel Backs Moderna’s Covid-19 Vaccine

“The evidence for the vaccine highly outweighs any issues that we have seen,” said panel member Hayley Gans, a Stanford University pediatrics professor.

The independent group of medical experts considered in depth the scientific results, including side effects, raised in Moderna’s clinical study of about 30,000 patients. The FDA doesn’t have to follow their advice, but it is expected to do so and is likely to act as early as Friday.

The Moderna vaccine has been shown to reduce the rate of Covid-19 disease with symptoms by 94.1% in the study, which compared the vaccine to a placebo. The FDA termed the vaccine “highly effective” in its analysis released Tuesday.

Vaccine distribution could begin as early as this weekend, as happened a week ago when the federal agency granted a clearance for wide use of the other vaccine, from Pfizer Inc. and BioNTech vaccine, last week.

Federal officials say they expect to distribute nearly six million doses of the Moderna vaccine to more than 3,200 locations around the U.S. in the initial batch, with distribution potentially starting within about 24 hours of FDA action.

Doses could start arriving at hospitals and other vaccination sites by Monday. More shipments will follow, and Moderna expects to deliver a total of 20 million doses by the end of December.

With both vaccines, which are given in two doses, federal officials expect to have enough this month to immunize about 20 million people, mostly health-care workers and residents of nursing homes and other long-term care facilities.

Moderna’s vaccine can be shipped and stored at higher temperatures than Pfizer’s, which requires special freezers and dry ice.

There isn’t enough evidence regarding the use of the vaccine in a pediatric population younger than 18, or in pregnant or breast-feeding women, Rachel Zhang, an FDA medical officer, told the panel.

The committee decision was to recommend the FDA issue an emergency-use authorization, a kind of faster clearance that is short of full FDA approval.

At Thursday’s hearing, an FDA vaccine official said the agency is studying two cases of serious allergic reactions in people who got the Covid-19 vaccine from Pfizer and BioNTech in Alaska, stressing that vaccination sites will be able to handle such reactions.

Doran L. Fink, deputy clinical director of the agency’s division of vaccines, Thursday asked an advisory panel to evaluate the side effects and other issues related to the vaccines. FDA officials said such allergic reactions are a known phenomenon with vaccines in general.

Dr. Fink said the agency has “robust safety and reporting systems” to monitor such issues, including the fact that vaccine recipients are asked to participate in an electronic safety reporting network.

Dr. Fink said the FDA was working with Pfizer to revise the written prescribing information and fact sheets distributed with Pfizer’s vaccine to underscore the need for post-vaccination monitoring and how to manage an immediate allergic reaction.

The Moderna vaccine, developed in collaboration with the National Institutes of Health, was tested in about 30,000 patients and found to be 94.1% effective at preventing Covid-19 with certain symptoms, including severe disease. The Pfizer vaccine was found to be 95% effective.

Moderna also presented preliminary data suggesting that the first dose of its vaccine could reduce coronavirus infections that have no symptoms. A member of the FDA panel, Patrick Moore, said this would be “important for control of the epidemic” because it could be a sign the vaccine reduces viral transmission.

The Moderna study found that the most common side effects included injection-site pain, fatigue, headache and chills. Severe adverse reactions were rare but occurred more frequently after the second dose than after the first dose.

Moderna’s vaccine “offers the potential to address the public health crisis of Covid-19,” Jacqueline Miller, a Moderna senior vice president and therapeutic area head for infectious diseases, told the FDA committee members Thursday.

Moderna said there was one anaphylactic reaction in a vaccine recipient in the study, but it occurred two months after the second dose in a person with a history of asthma and allergy to shellfish. The company plans to continue to monitor for such events.

The Moderna vaccine would be the first of several after Pfizer’s vaccine that are expected to build up the nation’s vaccine supply against the coronavirus pandemic, which has killed more than 305,000 Americans and 1.6 million people world-wide, according to Johns Hopkins University.

One thorny issue the panel will confront is whether placebo patients in the Moderna and Pfizer studies will automatically now get vaccinated. Ethical considerations suggest that they should, having sacrificed for the public. But a countervailing force is that researchers need to follow those patients as long as possible to be a comparison group to assess side effects of the vaccines.

Moderna is exploring changing the design of its large study to offer its vaccine to people who previously received the placebo, to encourage them to remain in the study, the FDA said in a briefing document released earlier this week. This would allow Moderna to continue to collect safety and effectiveness data over a longer time frame than if placebo recipients were to drop out of the trial and take Pfizer’s vaccine or any other vaccine that may be authorized in the future, according to the document.

Write to Thomas M. Burton at [email protected] and Peter Loftus at [email protected]