Two doses have little effect on those under 5; results from testing three doses are weeks away. Liberal-leaning states like New York, Illinois and Massachusetts are letting mask mandates expire, getting ahead of federal guidance.
Scientific advisers to the Food and Drug Administration will decide next week whether to endorse giving two doses of the Pfizer-BioNTech coronavirus vaccine to children 6 months to 4 years of age, before clinical trials have shown whether a full course of three doses is effective. Such an authorization would be a first for the agency, many experts say.
Interim results suggested that two doses of the vaccine did not produce a strong immune response in children aged 2 through 4. Results from trials of the third dose are expected in a few weeks.
The companies applied for authorization for the two doses at the urging of the F.D.A., which was also highly unusual.
The fast-moving pandemic has forced federal health officials to make important decisions with limited data before, and they argue that it’s important to begin vaccinating young children now, before a new, potentially more dangerous variant arrives.
But the agency’s review of incomplete data as a basis for authorization has alarmed some experts.
“We’ve never done that before, that’s what gives me some pause,” said Dr. Gregory Poland, founder and director of the Mayo Vaccine Research Group in Minnesota and editor in chief of the journal Vaccine. “I don’t like that there isn’t more data.”
The third dose is likely to build up immunity in young children, Dr. Poland and several other experts said, but it is not guaranteed to do so. With the ebbing of the Omicron surge, many scientists feel the agency could afford to wait for results on the third shots, which are expected in just a few weeks.