WASHINGTON, Feb 11 (Reuters) - A US decision on Pfizer and BioNTech's COVID-19 vaccine for children 6 months through 4 years of age has been postponed for at least two months after the Food and Drug Administration said it needed more data.

The FDA had planned to make a decision on the vaccine based on early trial data because of what it had called a great public health need due to the surge in infections caused by the Omicron variant of the coronavirus. The decision was slated for next week with a rollout starting as soon as Feb 21.

On Friday, the agency said it had reviewed new trial information that had come in since Pfizer and BioNTech's request for emergency authorisation and decided it needed more data before moving forward.

The FDA said parents anxiously awaiting the vaccine for their younger kids should be reassured that the agency is taking the time to make sure it meets the standard it has set for authorisation.

"If something does not meet that standard, we can't proceed forward," said Dr Peter Marks, director of the FDA’s Center for Biologics Evaluation and Research.

Pfizer and BioNTech had submitted data on the first two doses of what was planned as a three-dose regimen for this age group earlier this month at the request of the FDA. It did not disclose efficacy data.

The submission was surprising because in December, they said initial trial results of the lower-dose vaccine fell short of expectations in 2- to 4-year olds and amended its clinical trial to test a three-dose version of the shot.

The companies said they would continue the trial to dose all children with three shots and expected to have data in April.

"This is a three-dose vaccine, and they were going to be presenting data on the first two doses. It makes sense to wait for the safety and efficacy data on all three doses to be available before we make a decision about this vaccine," said Dr. Paul Offit from Children's Hospital of Philadelphia.

Offit is a member of the FDA's Vaccines and Related Biological Products Advisory Committee that had been scheduled to vote on whether to recommend authorisation of the shot for kids under 5 on Tuesday. The meeting was postponed.

"I'm not sure where this all came from. Why were we being asked to do this?" he said.