The FDA had planned to make a decision on the vaccine based on early trial data because of what it had called a great public health need due to the surge in infections caused by the Omicron variant of the coronavirus. The decision was slated for next week, with a rollout starting as soon as February 21.
The FDA said parents anxiously awaiting the vaccine for the roughly 18 million children in the age group should be reassured that the agency is taking the time to make sure it meets the standard it has set for authorisation.
Pfizer and BioNTech had submitted data on the first two doses of what was planned as a three-dose regimen for this age group earlier this month at the request of the FDA; they did not disclose efficacy data.
The submission was surprising because in December they said initial trial results of the lower-dose vaccine fell short of expectations in two- to four-year-olds and amended their clinical trial to test a three-dose version.
The companies said they would continue the trial to dose all children with three shots and expected to have data in April.
Offit is a member of the FDA’s Vaccines and Related Biological Products Advisory Committee that had been scheduled to vote on whether to recommend authorisation of the shot for kids under five on Tuesday. The meeting was postponed.
“I’m not sure where this all came from. Why were we being asked to do this?” he said.
The primary series of the Pfizer/BioNTech vaccine has been two doses in all older age groups. But in December, Pfizer changed the design of its clinical trial to test a third dose of the vaccine in the age group because the lower dose generated an immune response in two- to four-year-olds that was inferior to the response measured in those aged 16 to 25 in previous clinical trials.
In six- to 24-month-old children, the vaccine generated an immune response in line with 16- to 25-year-olds.
Still, Dr Amesh Adalja, an infectious disease expert at the Johns Hopkins Center for Health Security, said there was considerable pushback about the FDA’s decision to pursue authorisation so quickly, “as this age group is very low risk for severe disease and vaccine uptake in the five-11 [age group] has been very suboptimal”.
“It’s critical that people have confidence in the process if higher vaccine uptake is the goal,” Adalja said.