(CNN) — The US Food and Drug Administration is considering new rules for authorization for a Covid-19 vaccine, according to three sources familiar with the situation — and calculations show these rules would push an authorization beyond Election Day.
That would dash the hopes of President Trump, who has said repeatedly the vaccine could be ready by November 3.
The sources described two different scenarios that the FDA is assessing before a pharmacy company can be given an emergency use authorization for its vaccine.
“Either way, it’s going to be Thanksgiving at the earliest before a company gets an EUA,” the first source said.
That source said the FDA is expected to tell vaccine makers that they need to wait two months after giving all their study participants their second doses of the vaccine until they can apply for an EUA.
Pfizer and Moderna, the two companies that began Phase 3 clinical trial for coronavirus vaccines in the US in July, have given second doses to less than half their participants.
“They [the FDA] are strongly considering this move. They haven’t said the ‘thou shalt,’ but they are giving signals that this is important to them and they are moving in this direction,” the source said.
There’s a second scenario that might happen instead.
A second source, a senior administration official, said the agency is expected to require that companies wait 60 days after giving half their trial participants their second dose before they can secure an EUA. The move is designed to monitor the safety of the vaccine, even if the trial has already determined the vaccine’s efficacy.
Under that rule, the two companies still wouldn’t get an EUA by Election Day, since they have not yet given second doses to half their volunteers.
A third source said the FDA was considering making the 50% requirement, but that it was still in the discussion stage.
Pfizer plans to enroll 44,000 volunteers in its clinical trial, and as of Monday it had given second doses to 19,210 participants.
Moderna plans to enroll 33,000 volunteers in its clinical trial, and as of Friday, it had given second doses to 11,879 participants.
Both companies expect an initial readout of efficacy data, called an interim analysis, to occur in the coming weeks.
A third clinical trial by AstraZeneca is currently paused in the United States, after a participant in the UK developed a neurological condition.
News that the agency is expected to issue the new guidance to Covid-19 vaccine developers was first reported by the Washington Post on Tuesday.
FDA spokeswoman Stephanie Caccomo said in email to CNN on Tuesday, “FDA has previously noted that the agency intends to issue additional guidance shortly” with “recommendations regarding the data and information needed to support the issuance of an EUA.”
Dr. Peter Marks, who heads FDA’s Center for Biologics Evaluation and Research, which evaluates vaccines for approval, has previously said the standard for authorizing any eventual coronavirus vaccine will be like an “emergency use authorization-plus.” Marks said September 10 that the FDA requirements will be stricter than for an EUA for an experimental drug, but not as stringent as the requirements for full licensure.
“Given these trials we’re expecting that we’re going to have about a median — that is about 50% of people will have more, 50% of people will have less — than about two months of follow-up on people. That’s what we’re hoping for. It turns out that most of the adverse events that will occur after vaccination will occur in a timeframe of about a month and a half after vaccination,” Marks said. “At the time of an emergency use authorization there will be efficacy data that’s met an interim analysis end point and we have safety data that would be sufficient on a large number of people. We’re talking something on 15-to-20,000 people that will make us feel reasonably confident that we understand the safety profile of the vaccine.”
President Trump has made repeated claims that the United States is going to have a vaccine soon.
“We may very well have the vaccine prior to a certain very important date, namely November 3rd,” the President said on September 16 at a White House press briefing.