NEW YORK (AP) — The US on Saturday opened COVID-19 vaccines to infants, toddlers and preschoolers.

The shots will become available next week, expanding the nation’s vaccination campaign to children as young as 6 months.

Advisers to the Centers for Disease Control and Prevention recommended the vaccines for the littlest children, and the final signoff came hours later from Dr. Rochelle Walensky, the agency’s director.

“We know millions of parents and caregivers are eager to get their young children vaccinated, and with today’s decision, they can,” Walensky said in a statement.

While the Food and Drug Administration approves vaccines, it’s the CDC that decides who should get them.

The shots offer young children protection from hospitalization, death and possible long-term complications that are still not clearly understood, the CDC’s advisory panel said.

The government has already been gearing up for the vaccine expansion, with millions of doses ordered for distribution to doctors, hospitals and community health clinics around the country.

Roughly 18 million kids will be eligible, but it remains to be seen how many will ultimately get the vaccines. Less than a third of children ages 5 to 11 have done so since vaccination opened up to them last November.

Two brands — Pfizer and Moderna — got the green light Friday from the FDA and Saturday from the CDC. The vaccines use the same technology but are being offered at different dose sizes and number of shots for the youngest kids.

Pfizer’s vaccine is for children 6 months to 4 years old. The dose is one-tenth of the adult dose, and three shots are needed. The first two are given three weeks apart, and the last at least two months later.

Moderna’s is two shots, each a quarter of its adult dose, given about four weeks apart for kids 6 months through 5 years old. The FDA also approved a third dose, at least a month after the second shot, for children with immune conditions that make them more vulnerable to serious illness.