Covid Vaccines Must be Watched for Two Months Before FDA Review

The FDA will require makers of Covid-19 vaccine candidates to monitor their clinical trial participants for a median of two months after administering their last shot, a top agency official said.

The agency could shorten the time frame before it will consider authorizing the vaccine depending on what the data shows, Peter Marks, director of the Food and Drug Administration’s Center for Biologics and Evaluation Research, said during a JAMA Live event Monday.

“We’re not going to be completely flexible. It’s not like we’re going to take anything. That would be dangerous. On the other hand, if it turns out the median is seven weeks and not two months, that’s not going to be an issue,” Marks said.

Marks’s comments come less than two weeks after 60 leading researchers and bioethicists called on Pfizer Inc. to monitor clinical trial participants for at least two months following their second shot before submitting an application to the FDA to put the vaccine on the market..

Such a move would put the company into late November. The company had said it expects its clinical trial will yield conclusive results in October, putting it ahead of ahead of Moderna Inc. and AstraZeneca PLC and other promising vaccine candidates.

While it would be nice to have much more follow-up data, the two-month median is a move to balance the need to determine safety and efficacy with the need to respond urgently to the pandemic “that’s killing a thousands or more people a day in the U.S.,” Marks said.

Marks said he expects “we’ll see something before the end of the year,” but underscored that nothing is definite.

The companies determine upfront whether they are going for a full approval or an emergency use authorization. But Marks noted the safety and efficacy data required are very similar between the two. He described what’s required for a full approval as mostly “window dressing.”

The agency will require a higher bar for an emergency authorization of a vaccine, which is provided to healthy people compared with a therapeutic to treat critically ill patients who have no other option.

“The safety is clearly going to be something that we have to keep first in foremost,” he said, adding later that safety is the thing that keeps him up at night. “All we need is something happening with vaccine safety to have a real problem here.”

Acknowledging “we do have a crisis in vaccine confidence now,” he said the agency has been working diligently to increase public confidence and assure the public that career scientists, and not political appointees, are making regulatory decisions.