(NewsNation Now) — Pfizer and partner BioNTech have asked U.S. health regulators to approve emergency use of their COVID-19 vaccine for children aged from 5 to 11, Pfizer confirmed Thursday.

At this time, only children as young as 12 are able to get the Pfizer vaccine.

The Pfizer COVID-19 vaccine is the only vaccine approved by the Food and Drug Administration for Americans 16 years and up. Regulators have also approved emergency use authorization for kids 12-15 years old.

An emergency use authorization is when regulators allow shots to be given to certain people while studies of safety and effectiveness are ongoing. Instead of the usual requirement of “substantial evidence” of safety and effectiveness for approval, the FDA can allow products onto the market as long as their benefits are likely to outweigh their risks. It has already used its emergency powers to authorize hundreds of coronavirus tests and a handful of treatments during the pandemic.

Pfizer and BioNTech submitted data to the FDA last month from a trial on the effects of the vaccine on children.

For elementary school-aged kids, Pfizer tested a much lower dose — a third of the amount that’s in each shot given now. Yet after their second dose, children ages 5 to 11 developed coronavirus-fighting antibody levels just as strong as teenagers and young adults getting the regular-strength shots, Dr. Bill Gruber, a Pfizer senior vice president, told The Associated Press.

The kid dosage also proved safe, with similar or fewer temporary side effects — such as sore arms, fever or achiness — that teens experience, he said.

While kids are at lower risk of severe illness or death than older people, more than 5 million children in the U.S. have tested positive for COVID-19 since the pandemic began and at least 460 have died, according to the American Academy of Pediatrics. Cases in children have risen as the delta variant swept through the country.

This comes as California became the first U.S. state to require COVID-19 vaccinations for children to attend public and private schools in person, in an attempt to get the pandemic under control.

“We want to end this pandemic. We are all exhausted by it,” Gov. Gavin Newsom said during a news conference last week.

Exemptions would be granted for medical reasons or because of religious or personal beliefs but the exemption rules haven’t been written yet pending public comment. Any student without an exemption who refuses to get the vaccine would be forced to do independent study at home.

A second U.S. vaccine maker, Moderna, also is studying its shots in elementary school-aged children. Pfizer and Moderna are studying even younger tots as well, down to 6 months old. Results are expected later in the year.

This story is developing. Refresh for updates.

The Associated Press contributed to this report.