FDA Open to Less Than 50 Percent Efficacy in COVID Vaccines for Smallest Kids

In a May 6 briefing before Congress, the director of the FDA’s Center of Biologics Evaluation and Research (CBER), Peter Marks, said the agency would not withhold authorization for a pediatric vaccine solely because it did not reach a 50 percent efficacy threshold at blocking symptomatic infection — a requirement that had been previously listed in FDA guidance.

The vaccines currently authorized by the FDA have proven to be less effective at preventing symptomatic infection from the Omicron variant when compared to the original strain but still remain effective at reducing the risk of severe disease.

“If these vaccines seem to be mirroring efficacy in adults and just seem to be less effective against Omicron like they are for adults, we will probably still authorize,” said Marks in a readout of the briefing.

The FDA did not respond to our request for a full transcript of the briefing.

In his remarks, Marks also said the FDA would “look carefully at all data” when assessing the vaccines, including the efficacy against severe disease, and added that “the goal here is to get some protection in sooner rather than later.”

The briefing on the status of coronavirus vaccine candidates for young children took place before the Select Subcommittee on the Coronavirus Crisis.

The briefing came after Rep. James Clyburn (D-S.C.), chairman of the subcommittee, sent a letter to FDA Commissioner Robert Califf on April 25 reacting to reports that the agency was considering delaying its review of the first coronavirus vaccine for children under six years old (DID, April 29).

“Parents of young children across America have been waiting for more than two years for the peace of mind that a safe and effective coronavirus vaccine provides,” said Clyburn in a statement after Marks’ briefing. “They deserve to know that FDA is doing everything in its power to review and authorize pediatric vaccines as quickly as the science allows.”

However, in an April 26 hearing before the Senate Committee on Health, Education, Labor and Pensions (HELP), Marks in effect blamed the vaccine developers, saying the FDA hadn’t received full and complete applications from any companies seeking approval for COVID-19 vaccines in the youngest pediatric group, and without those complete applications, the agency can’t begin its review.

Moderna announced just after that statement that it had filed for Emergency Use Authorization (EUA) of its two-dose COVID-19 vaccine in children less than six years old, and Pfizer and BioNTech are expected to file for an EUA next month for a three-dose vaccine in children under five years old. In addition, Novavax’s protein-based COVID-19 vaccine is likely to be considered. The company requested an EUA in January and is working on a rolling submission, a company spokesperson told FDAnews.

Early this month, the FDA announced tentative dates for its vaccine-related advisory committee to meet to discuss the much-anticipated full applications for EUAs that it expects any day from COVID-19 vaccine manufacturers for children under age six (DID, May 2).

In the May 6 briefing, Marks also said the FDA will move up its advisory panel’s deliberations on vaccines for young children if the agency reviews are completed sooner than expected. — Suz Redfearn