Pfizer tests extra COVID shot for kids under 5 in setback

By LAURAN NEERGAARD AP Medical Writer

Pfizer is testing an extra dose of its COVID-19 vaccine for babies and preschoolers after preliminary research hinted the usual two doses wouldn't be enough.

Pfizer had been testing very low-dose shots in children under age 5, with some data expected by year's end.

But Pfizer and its partner BioNTech announced Friday the change to its ongoing study after a preliminary analysis found 2- to 4-year-olds didn't have as strong an immune response as expected — although babies and toddlers reacted well.

It's not clear how much the setback will delay the quest for vaccinating the youngest children.