FDA issues updated guidance on adapting Covid-19 vaccines, tests and therapeutics for coronavirus variants

The US Food and Drug Administration has issued updated guidance for companies that plan to adapt their Covid-19 medical products — including vaccines, tests and therapeutics — to address the emergence of coronavirus variants.

The agency said in an announcement on Monday that it expects that “manufacturing information will remain generally the same” for authorized Covid-19 vaccines that may be updated to target variants. The agency recommended that data from clinical immunogenicity studies be used to support any changes or updates to vaccines.

Such studies would be smaller and could take less time than large-scale clinical trials.

“It’s going to be on the order of a few hundred individuals in terms of size and we’d expect that that might take a few months,” Dr. Peter Marks, director of the FDA’s Center for Biologics Evaluation and Research, said during a call with reporters on Monday.

“For clinical data, the guidance recommends that a determination of effectiveness be supported by data from clinical immunogenicity studies, which would compare a recipient’s immune response to virus variants induced by the modified vaccine against the immune response to the authorized vaccine,” the agency noted in its announcement.

According to the FDA guidance, studies to assess the effectiveness of a Covid-19 vaccine’s primary shot and booster dose should compare the immune response induced by the modified version of the vaccine to the original vaccine, and researchers should conduct a “booster study” in which the modified vaccine is administered to those who previously received the original vaccine.

“Each of the studies described above may be conducted in a single age group,” the guidance said. Those results can then be extrapolated to other age groups for which the original vaccine has been authorized — and to previously infected people in those age groups.

The agency released separate guidance for Covid-19 tests and therapeutics too.

“The FDA is committed to identifying efficient ways to modify medical products that either are in the pipeline or have been authorized for emergency use to address emerging variants,” Dr. Janet Woodcock, acting commissioner of the FDA, said in the announcement on Monday.

“We know the country is eager to return to a new normal and the emergence of the virus variants raises new concerns about the performance of these products,” Woodcock said in part. “By issuing these guidances, we want the American public to know that we are using every tool in our toolbox to fight this pandemic, including pivoting as the virus adapts.”

FDA officials said during Monday’s call that some of the updated guidance for Covid-19 vaccines is modeled after what is already done for the development of seasonal influenza vaccines.

“We have experience with the fact that viruses change over time and seasonal influenza changes very frequently,” Woodcock said during the call.

Marks added, “What we’re doing here that’s similar is trying to leverage the change with the minimal amount of extra data that we need to facilitate things. We’re trying to prepare in advance, like we would for influenza.”