An advisory panel to the U.S. Centers for Disease Control and Prevention (CDC) on Thursday voted to recommend COVID-19 vaccine booster shots for children ages 5 to 11, at least five months after completing their primary vaccination course.

The advisers considered data from the CDC that showed protection from two doses starts to wane over time, and that boosters in older age groups improved efficacy against severe COVID and hospitalizations.

CDC Director Rochelle Walensky still needs to sign off on the committee's recommendation, but signaled at the meeting that she was likely to back the additional shots.

"We know immunity wanes over time, and we need to do all we can now to protect those most vulnerable," Dr. Walensky said. "It's important for us to anticipate where this pandemic is moving and deploy the tools we have where they will have the greatest impact."

Just over 29% of U.S. children ages 5-11 are considered fully vaccinated with two doses of the Pfizer/BioNTech shot. The vaccine is not yet authorized for children younger than 5.

The committee voted 11 to 1 to recommend the additional shots, with one doctor abstaining.

Dr. Helen Keipp Talbot was the lone committee member to vote against recommending the boosters, arguing that the focus should be on increasing the vaccination rate in the age group.

"Boosters are great once we've gotten everyone their first round," she said.