The Food and Drug Administration postponed an upcoming and long-awaited review of COVID-19 vaccines for kids under 5 years old because it needs more data, and now the review may not take place until at least April.

The FDA had planned to meet on Feb. 15 to review a two-dose regimen of the Pfizer shots for young children ages 6 months to 4 years old, but officials on Friday said the agency needs more time to evaluate a three-dose regimen instead. Pfizer said it would probably have additional data on the third shot by April.

“We are committed to moving as rapidly as we can once we have a submission,” Peter Marks, director of the FDA’s Center for Biologics Evaluation and Research, told reporters Friday, adding that he believes officials “owe it to the parents of small children” to move as quickly as they can.

Earlier this month, Pfizer-BioNTech submitted an emergency use application to the FDA for two 3-microgram doses of its COVID-19 shot as part of a three-dose primary series. But in the initially scheduled review, FDA vaccine advisers planned to look at and potentially authorize the first two shots, hoping data would come soon on the third shot.

Marks said data from the omicron surge proved it did not make sense to authorize the initial two shots without the third. He would not reveal more information on the data, though, on the call with reporters.

In the meantime, the FDA encourages parents of young kids to keep taking the preventive measures they’ve been adhering to for the past two years, such as social distancing and wearing masks.