Moderna Inc’s COVID-19 vaccine appeared to be set for regulatory authorization this week after U.S. Food and Drug Administration staff members did not raise any major new concerns about it in documents released on Tuesday.
The FDA reviewers said a two-dose regimen of Moderna’s vaccine was highly effective in preventing confirmed cases of COVID-19 and did not raise any specific safety issues with using the vaccine in adults over the age of 18.
The comments were made in documents prepared for Thursday’s meeting of outside experts, who will discuss whether to endorse a U.S. emergency use authorization (EUA) for the Moderna shot.
The FDA typically follows the advice of the panel, but is not required to do so.
Moderna’s is the second vaccine the FDA has considered, behind one from Pfizer Inc. and Germany’s BioNTech, which was authorized last week.
Hospitals began giving the Pfizer shots on Monday and the United States is counting on the Moderna vaccine to fulfill its promise to inoculate 20 million people this month.
The FDA said that there appeared to be some protection for trial participants after the first dose of Moderna’s vaccine, which is given in two shots, with 28 days between inoculations, but there was not enough information on longer term protection.
It said that vaccine efficacy was 80.2% in participants who only received one dose at the time of the interim analysis, which was based on data collected as of Nov. 7.
They said that serious side effects in the trial of the vaccine represented medical events that occur in the general population at a similar frequency as observed in the study.
The FDA did flag the possibility that the vaccine was contributing to Bell’s palsy, a type of facial paralysis also reported by participants in the Pfizer trial.
Moderna reported four cases of Bell’s palsy, including three among people who had the vaccine and 1 in the placebo group. The company said that three of the cases had resolved itself.
Although the FDA said that the trial participants with Bell’s palsy had predisposing factors, the “potential contribution of the vaccine to the manifestations of these events of facial palsy cannot be ruled out”.
Pfizer reported six cases of Bell’s palsy, including 4 in the vaccine arm, which it said was a rate typical of the general population.
Moderna shares, which have risen nearly eight-fold this year up to Monday’s closing price, were up 1.8% before the bell.