Washington (AFP) - The US Food and Drug Administration (FDA) on Friday announced it was postponing a meeting scheduled for next week where a panel of experts would have decided whether to endorse the Pfizer-BioNTech Covid vaccine for infants.
Both the FDA and Pfizer-BioNTech now say they want to wait for results of three doses among children aged six months through four years, rather than look to authorize a two-dose series -- meaning a final decision could take several more weeks.
"The companies expect to have three-dose protection data available in early April," the US and German pharmaceuticals said in a statement.
"Given that the study is advancing at a rapid pace, the companies will wait for the three-dose data as Pfizer and BioNTech continue to believe it may provide a higher level of protection in this age group."
The news will likely disappoint many parents of small children, who have already waited many months to immunize their families.
But the decision to hold the meeting -- originally scheduled for Feebruary 15 -- in the first place had been contentious and regarded as premature by some of the scientific community.
Interim results announced in December had shown that a low dose of three micrograms given to children aged six months to two years elicited a similar level of antibodies to the full 30 micrograms given to people aged 16-25, but the same was not true for children between two and four.
Three micrograms was chosen for safety reasons, since side-effects like fevers are considered much more serious among infants than older children and adults.
It was then decided to add a third shot to their series -- but in an unusual move made during the Omicron surge, as pediatric hospitalizations rose dramatically, the FDA asked Pfizer and BioNTech to file for authorization for two shots anyway.
It was suggested this would allow the vaccination series to start sooner rather than later, then the authorization could be amended later on to require three shots.
Attempting to explain the reversal, FDA scientist Peter Marks said: "What I can say is that the data that we saw made us realize that we needed to see data from my third dose."
He also indicated that, rather than relying on detecting immune responses among trial participants, the extra time spent on the study would generate a vaccine efficacy figure too.
The decision comes as Omicron infections are receding fast, though overall case numbers remain high.
