Pfizer will change plans and test three doses of its Covid-19 vaccine in babies and preschoolers after the usual two shots didn't appear strong enough for some of the children.
Pfizer announced the change after a preliminary analysis found 2- to 4-year-olds didn't have as strong an immune response as expected to the very low-dose shots the company is testing in the youngest children.
It's disappointing news for families anxious to vaccinate their tots. Pfizer had expected data on how well the vaccines were working in children under 5 by year's end, and it's not clear how long the change will delay a final answer.
Pfizer and its partner BioNTech said if the three-dose study is successful, they plan to apply for emergency authorisation sometime in the first half of 2022.
A kid-sized version of Pfizer's vaccine already is available for 5- to 11-year-olds, one that's a third of the dose given to everyone else 12 and older.