Three doses of Pfizer’s COVID-19 vaccine offer strong protection for children younger than 5, the company announced Monday. Pfizer plans to give the data to U.S. regulators later this week in a step toward letting the littlest kids get the shots.

The news comes after months of anxious waiting by parents desperate to vaccinate their babies, toddlers and preschoolers, especially as COVID-19 cases once again are rising. The 18 million tots under 5 are the only group in the U.S. not yet eligible for COVID-19 vaccination.

The Food and Drug Administration has begun evaluating data from rival Moderna, which hopes to begin offering two kid-sized shots by summer.

Pfizer has had a bumpier time figuring out its approach. It aims to give tots an even lower dose — just one-tenth of the amount adults receive — but discovered during its trial that two shots didn’t seem quite strong enough for preschoolers. So researchers gave a third shot to more than 1,600 youngsters — from age 6 months to 4 years — during the winter surge of the omicron variant.

Read the full Madison.com press release here