FDA to weigh toddler vaccines by June

WASHINGTON — The Food and Drug Administration on Friday laid out a tentative timetable for deciding whether to authorize a coronavirus vaccine for America’s youngest children, announcing that June 8 is the earliest date that it will present data to its outside advisers for a recommendation.

The nation’s 18 million children younger than 5 are the only group not yet eligible for vaccination against the coronavirus.

The agency said it understood the urgency of protecting that group and that it would act quickly “if the data support a clear path forward following our evaluation.”

The FDA laid out a packed June schedule, setting aside three days for its outside advisory committee to consider the pediatric vaccine applications from Moderna and PfizerBioNTech, and another day to debate and presumably vote on proposals to update existing vaccines so they work better against a range of coronavirus variants. The dates are tentative, the agency said, because the companies have not yet completed their applications for emergency authorization.

The agency’s release of a schedule came after some critics raised concerns that it was delaying action on Moderna’s application in order to compare it with data from Pfizer, which is not expected in full until June. The FDA commissioner, Robert Califf, said that was not the case in interviews Thursday and Friday.

“Categorically, there is no reason for the FDA to wait,” he told Andy Slavitt on the podcast “In the Bubble.” In an emailed response to questions, Dr. Peter Marks, who oversees the agency’s vaccine regulation, said that regulators “will not hold up moving forward on any request just to synchronize things.”

Moderna said Thursday that it had asked the FDA to authorize its vaccine for children 6 months to 6 years old, saying its clinical trial showed the vaccine was safe and produced an antibody response comparable to that of adults ages 18-25. That met the trial’s criterion for success. It said the vaccine appeared to be 51 percent effective against symptomatic infection among those younger than 2, and 37 percent effective among those ages 2-5.

Those efficacy rates are far below those of earlier clinical trials conducted by both Moderna and Pfizer before the highly transmissible omicron variant emerged. Omicron and its subvariants have proved far more adept at evading protection from antibodies that constitute the immune system’s first line of defense against infection.

Because there were no cases of serious illness or hospitalization among any of the trial participants, it was not possible to judge how well the vaccine protects against COVID-19’s worst outcomes.

Moderna said it would finish submitting its data to the FDA by May 9. Pfizer and BioNTech are expected to complete their application to vaccinate children younger than 5 in June. The vaccine regimens are different: Moderna is proposing two doses, using one-fourth the strength of an adult dose. Pfizer and BioNTech are working on a threedose regimen, at one-tenth the strength of the adult dose.

Pfizer’s vaccine is already authorized for everyone 5 years and older, while Moderna’s shots are limited to adults. Moderna has previously requested authorization of its vaccine for children between the ages of 6 and 17. The company said it plans to submit data supporting and updating those requests in about two weeks.

The agency set June 28 for the advisory committee to consider how best to update the existing vaccines. Researchers working for the National Institutes of Health and vaccine manufacturers have been racing to try to redesign the vaccines so they are more effective against newer virus variants. Federal health officials have said they need to choose one or more revised versions by June in order to manufacture doses by the fall, when they expect the coronavirus to resurge.

The agency also said that it plans to present vaccine data June 7 from Novavax, which has developed a vaccine using a more conventional approach than the PfizerBioNTech and Moderna shots that have now been used to inoculate hundreds of millions of Americans.