The White House expects to begin COVID vaccinations for children under age 5 as soon as June 21, a senior Biden administration official said last week, as the U.S. prepares for Pfizer (PFE  ) and Moderna (MRNA  ) shots to be authorized for the youngest Americans this month.

To do this, the Biden administration is making 10 million doses of Pfizer and Moderna vaccines now available to states, pharmacies and community health centers to order, White House COVID response coordinator Dr. Ashish Jha told reporters. The vaccine doses will ship out once the U.S. Food and Drug Administration (FDA) authorizes the doses, Jha added.

Children under age 5 are the only group ineligible for COVID vaccination. While COVID infections have been generally less severe in children than adults, children were impacted more by the Omicron variant than previous variants and the Biden administration it looking to protect the entire population from community outbreaks.

Pfizer has submitted data from its clinical trial of children ages 6 months through 4 years old to the FDA to expand its vaccine's emergency use authorization (EUA). The company found that three shots of three microgram doses--one-tenth the dosage approved for adults--was 80% effective at preventing symptomatic infection from the Omicron variant.

Similarly, Moderna's two-dose vaccine at about one-fourth the dosage of the approved adult shot was about 51% effective against Omicron infection in children under 2-years-old and 37% effective for children between the ages of 2 and 5 years, the company's clinical trial showed.

The FDA is expected to make a decision on both shots next week, after the agency's independent vaccine advisory committee makes a recommendation after reviewing the submitted data at the conclusion of its meeting on June 15. From there, the U.S. Centers for Disease Control and Prevention (CDC) will issue its recommendations quickly as the FDA's decision.