Pfizer Inc. and partner BioNTech SE said they have begun submitting data to U.S. regulators for authorization of their COVID-19 vaccine in younger children, hastening an effort to get shots to more kids after the omicron wave caused pediatric infections to jump.

The companies said in a statement that they have started a so-called rolling submission with the U.S. Food and Drug Administration seeking an emergency authorization for the vaccine in children ages 6 months to 4 years. A panel of outside advisers is scheduled to meet Feb. 15 to consider the request, according to a statement from the agency.

“Having a safe and effective vaccine available for children in this age group is a priority for the agency and we’re committed to a timely review of the data,” Acting Commissioner Janet Woodcock said in the statement.

The clearance request came earlier than expected.

Data released by the companies in December suggested that the ability of two doses to prevent infection was mixed and that more evidence would be needed before asking for an authorization. The companies said at the time that they would study a third dose and, if successful, seek authorization in the first half of 2022.

However, Pfizer and BioNTech accelerated that timetable at the request of regulators.

The FDA asked the drugmakers to submit data on two doses of the shot as part of a three-dose series, according to the statement. Data on a third dose given eight weeks after the second shot are expected in coming months and will also be sent to regulators, the companies said.

With cases surging this winter, more kids have been infected with the virus, complicating child care and parents’ efforts to remain at work.

At the same time, however, there are signs that families are more wary of getting shots for younger kids.

While vaccines have been available for children ages 5 to 11 for several months, vaccination rates in that group remain lower than in older demographics even amid signs that the omicron strain leaves kids at greater risk of disease. Virus cases among children have risen since omicron was first detected in the U.S. in December, with pediatric hospitalizations reaching a record at the end of last year.

In December, Pfizer vaccine executive Kathrin Jansen said that limiting the spread of the more infectious omicron variant, which currently accounts for almost all COVID-19 cases, “may only be possible with three or more doses.”

Three shots are now recommended by the Centers for Disease Control and Prevention for everyone 12 and older, and it is expected that third shots will be cleared for those 5 and up soon. While U.S. regulators consider anyone who has received two doses of a messenger RNA shot to be fully vaccinated, studies have shown three doses are more effective at shielding against an omicron infection.