It's a crucial step in obtaining federal regulatory clearance to get young kids vaccinated and controlling the pandemic.
The U.S. is unlikely to achieve herd immunity until children can get vaccinated, public health officials and infectious disease experts say.

Pfizer said it has started a clinical trial testing its Covid-19 vaccine on healthy 6-month to 11-year old children, a crucial step in obtaining federal regulatory clearance to start vaccinating young kids and controlling the pandemic.

The first participants in the study have already gotten their shots, which were developed in partnership with German drugmaker BioNTech, New York-based Pfizer announced Thursday. It intends to enroll 144 children in the first phase.

For the first phase of the trial, the company will identify the preferred dosing level for three age groups – between 6 months and 2 years old, 2 and 5 and from 5 through age 11. The kids will begin by receiving a 10 microgram dose of the vaccine before progressively moving to higher doses, Pfizer said. Participants also have the option to take 3 microgram doses. The Covid vaccine for adults requires two shots that contain 30 micrograms per dose.