Children under age 5 became eligible for the COVID-19 vaccine as soon as this weekend, after the U.S. Food and Drug Administration gave its approval Friday for the age group.

The FDA announced that it would amend its emergency use authorization for the vaccines developed by Moderna and Pfizer-BioNTech, making both of them available to children as young as 6 months old.

This weekend, officials with the U.S. Centers for Disease Control and Prevention endorsed the recommendation to authorize the shots for the country's youngest children.

Toddlers and young children could begin receiving COVID vaccine doses by Monday or Tuesday as a result.

"Many parents, caregivers and clinicians have been waiting for a vaccine for younger children and this action will help protect those down to 6 months of age," FDA Commissioner Dr. Robert Califf said in a statement. "As we have seen with older age groups, we expect that the vaccines for younger children will provide protection from the most severe outcomes of COVID-19, such as hospitalization and death."

The Pfizer vaccine will be administered to children under age 5 in three doses over roughly three months while the Moderna vaccine will have the same two-dose schedule for all children.

The Pfizer-BioNTech vaccine is currently approved under an emergency use authorization for everyone ages 5-15 and fully approved and marketed as Comirnaty for everyone ages 16 and up.

The Moderna vaccine has also been fully approved for all adults and is marketed as Spikevax.

According to CDC data, 66.8% of all U.S. residents have completed their initial vaccination series.