Pfizer-BioNTech is expected to request emergency use authorization for its vaccine to the U.S. Food and Drug Administration as early as today, several outlets have reported. The vaccine could become available as early as the end of February. 

If approved, it would become the first vaccine available to children 6 months to 5 years old in the U.S., which is the last age group currently ineligible to receive a COVID-19 vaccine. The news was first reported by The Washington Post. Emergency use authorization would allow for young children to begin a two-dose vaccine regimen, and does not include the booster shot. 

Pfizer-BioNTech is still testing the safety of a third booster shot for children under five years old, but emergency use authorization of the first two doses will provide initial immunity support, and prepare children to receive a third shot if and when there is more data to support its effectiveness, according to the Post.  

Pfizer’s request for FDA authorization for a vaccine for young children—which follows the FDA’s urging to begin the process—comes at a critical time.

Earlier this month, after Omicron became the dominant variant in the U.S., the number of hospitalized children infected with COVID-19 rose to the highest levels seen since the beginning of the pandemic. While Omicron appears to be less severe for vaccinated people, the same is not true for those who are unvaccinated, which includes all children under 5. 

While the number of children hospitalized with COVID has declined since the first week of January, it is still well above the levels seen during previous COVID waves, according to data from the Centers for Disease Control and Prevention. 

The CDC said in a press conference this month that a lack of vaccination eligibility is a likely reason for the increased hospitalization of children, though there was no evidence to suggest Omicron was more likely to produce a severe reaction in children under 5 than it would in an adult.

Overall, vaccination rates for children remain low compared to the general population, despite the FDA authorizing vaccines for children ages 5 to 11 last October. Only around 30% of children in that age group have received at least one dose, as of Jan. 31, according to the CDC. 

Until the vaccine is approved for children under 5, health experts are urging parents to get vaccinated and to vaccinate their children who are eligible.

“Please, for our youngest children, those who are not yet eligible for vaccination, it’s critically important that we surround them with people who are vaccinated to provide them protection,” CDC director Rochelle Walensky said earlier this month.