Ex-FDA chief: Vaccine for kids under 5 could come earlier than expected

Driving the news: Previously, Gottlieb said vaccines could get out by late March at the very earliest, depending on regulatory approval.

• But, he said, that timeline was based on the fact Pfizer expanded clinical trials on kids in December to three doses, instead of two, based on regulators' recommendation.

What he's saying: "Previously, we had data showing that the childhood vaccine for six months to four years wasn't as protective against infection as the adult vaccine. That's the reason they pushed it out," Gottlieb said.

• "But now, if the goal of the vaccine is to get baseline immunity into the kids to prevent bad outcomes and you're really not using the vaccine as a tool to prevent infection in the first place, two doses could do that," he said. "I think that may be why federal health officials are rethinking this."