US drugmaker Pfizer said Thursday it has formally requested emergency use authorization for its Covid-19 vaccine in children age five to 11.

Children have been infected in greater numbers in the latest coronavirus wave driven by the Delta variant, and inoculating young people is seen as key to keeping schools open and helping end the pandemic.

In late September, Pfizer and BioNTech, which co-developed the vaccine, began submitting data to the Food and Drug Administration regulators for the highly anticipated authorization.

Pfizer tweeted early Thursday that the two companies had "officially submitted our request" to the FDA "for Emergency Use Authorization (EUA) of our #COVID19 vaccine in children 5 to <12."

"We're committed to working with the FDA with the ultimate goal of helping protect children against this serious public health threat," Pfizer said.

Following the announcement White House Covid coordinator Jeff Zients told CNN that "I think we can all agree that getting a safe and effective vaccine for kids five to 11 is a really important next step in our fight against the virus."

Children in the 5-11 age group received a two-dose regimen of 10 micrograms in the trial, compared with 30 micrograms for older age groups. The shots were given 21 days apart.

The FDA has previously said that once the formal submission was completed, the agency would complete its review "likely in a matter of weeks rather than months."

The Pfizer-BioNTech vaccine has been granted full FDA approval for those age 16 and up.