- A review by Food and Drug Administration scientists appeared to support Pfizer and BioNTech's claim their experimental coronavirus vaccine is highly protective against COVID-19, raising no major issues that would derail an expected emergency clearance of the shot in the coming weeks.
- The detailed analysis by agency staff, released Tuesday ahead of a key meeting of FDA advisers later this week, uncovered no notable safety concerns and affirmed the drugmakers' finding that their vaccine is 95% effective in preventing symptomatic coronavirus disease.
- The analysis, along with a detailed presentation of data from Pfizer and BioNTech, will be discussed Thursday by an independent advisory committee tasked with reviewing the companies' application for an emergency use authorization, or EUA. The meeting is viewed as an important tool in building public confidence in the FDA's review process, although the agency is not required to follow the advisers' recommendations.
The documents released Tuesday are the most detailed look yet at the outcome of a large, late-stage study of Pfizer and BioNTech's coronavirus vaccine. Nearly 44,000 volunteers enrolled in the trial, results from which were released in November.
Over 53 pages, FDA reviewers methodically lay out an array of data supporting a clear conclusion: Two shots of the companies' experimental shot are strongly protective against COVID-19 regardless of age, gender, or racial or ethnic identity.
The data show only eight participants who received the vaccine got COVID-19, compared to 162 of those given placebo. In adults older than 55, a key demographic that's at higher risk of poor outcomes from the disease, vaccine efficacy was 94%, according to the documents.
An analysis by FDA staff also suggested protection could begin after the first shot, although the data indicate efficacy is lower, possibly around 52%, without the booster.
Agency reviewers warned against drawing any conclusions on the efficacy of a single dose, however, as most participants received their scheduled second shot after three weeks, limiting the follow-up observation.
While vaccination typically results in a range of fever-like symptoms that can be more severe in a small percentage of people, "no specific safety concerns [were] identified that would preclude issuance of an EUA," agency staff wrote.
The analysis did note four cases of Bell's palsy, a temporary condition that causes one side of the face to droop, among participants given vaccine, compared to zero in the placebo group. Despite the imbalance, the frequency among those on vaccine was not higher than the expected rate for the general population, the FDA said.
More instances of swollen lymph nodes were also observed in vaccinated participants.
The documents are "very simple and straightforward, which we think will lead to approval imminently," wrote Michael Yee, an analyst at Jefferies, in a note to clients. U.S. health officials have suggested in recent days that an authorization for Pfizer and BioNTech's vaccine could quickly follow Thursday's advisory committee meeting.
Emergency clearances — special approvals granted by the FDA during a public health emergency — are not equivalent to a full approval. But the FDA, conscious of public perception of a rushed vaccine development process and wary of clearing a shot for use in tens of millions of people on limited evidence, beefed up its requirements for granting an EUA to vaccines.
In addition to results showing vaccination could prevent COVID-19 in more than 50% of people, the agency required developers submit a median of two months of safety follow-up across their trial's participants. Most adverse reactions to vaccines occur within 40 to 60 days after administration, meaning a two-month median would give the agency a good sense of whether an experimental shot is safe.
Pfizer and BioNTech's vaccine clears both bars, although the data the companies have in hand still leaves a number of questions unanswered. Agency staff noted in their review that it's still unclear how long protection against COVID-19 will last and whether vaccination can prevent virus transmission or asymptomatic disease.
The data indicate that Pfizer and BioNTech's vaccine could protect against severe COVID-19 as well as more mild cases, although the FDA reviewers cautioned that the totality of evidence supporting this is small.
Should the advisory committee support, and the FDA authorize, Pfizer and BioNTech's vaccine, the companies would quickly begin distributing supplies across the U.S. Under an EUA, the federal government would decide how many doses each state receives.
About 6 million doses are expected to be ready for use in the U.S. if authorization is granted soon after Thursday's meeting. Pfizer and BioNTech have said they can produce 50 million doses globally by the end of the year, half of what they initially expected they could manufacture.
In July, the U.S. pre-ordered 100 million doses from Pfizer and BioNTech, with an option to buy up to another 500 million. According to The New York Times, however, the U.S. passed on opportunities this summer to lock in those additional doses. Senior administration officials disputed the Times' account on a call with reporters Monday.
The FDA is also reviewing an experimental vaccine from the Cambridge, Massachusetts-based biotech Moderna. The advisory committee reviewing Pfizer and BioNTech's candidate is set to meet again on Dec. 17 to discuss Moderna's application.
Moderna has said it can produce 20 million doses of its shot for the U.S. by the end of this year, and between 85 million to 100 million from January to March.
A Centers for Disease Control and Prevention panel last week recommended prioritizing the first supplies for healthcare workers and nursing home residents.
Editor's note: This article has been updated throughout with more details from the Food and Drug Administration's documents.