Pfizer and BioNTech plan to submit a request for emergency use authorization for their COVID-19 vaccine in children six months to 5 years old as soon as Tuesday, which could set the vaccine up to be approved for young children in the coming weeks, the Washington Post reports. 

The companies began a clinical trial last year to examine the effects of two doses of 3-microgram shots in children younger than 5. 

Dr. Manjul Shukla transfers Pfizer COVID-19 vaccine into a syringe, Thursday, Dec. 2, 2021, at a mobile vaccination clinic in Worcester, Mass. ((AP Photo/Steven Senne))

The vaccine is already approved for emergency use in children between the ages of 5 and 11, who receive 10 microgram doses. Children older than 12 and adults receive 30 microgram doses. 

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Two 3-microgram doses were found to be effective in children between six months and 2 years old, but children between the ages of 2 and 5 did not have the same immune response as the larger two-dose series in older children. 

21/12/25: A tray with vials containing Pfizer/BioNTech COVID-19 booster vaccine seen at a vaccination center. ( Dinendra Haria/SOPA Images/LightRocket via Getty Images)

That finding prompted Pfizer to study the administration of a third 3-microgram dose two months after the last dose. 

The FDA urged Pfizer and BioNTech to go ahead and submit the two-dose data so the approval process could begin, according to the Washington Post

Leah Lefkove, 9, covers her face as her dad Dr. Ben Lefkove gives her the first COVID-19 vaccine at the Viral Solutions vaccination and testing site in Decatur, Georgia. (AP Photo/Ben Gray)

Pfizer's vaccine was authorized for children between the ages of 5 and 11 in late October. 

About three months later, only 8.7 million children between the ages of 5 and 11 have received at least one dose and 6.2 million are fully vaccinated. 

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There have been 11.4 million COVID-19 cases in children since the pandemic began, making up about 18.6% of all cases, but children only represent 1.6%-4.4% of all COVID-19 hospitalizations and 0.00%-0.25% of all COVID-19 deaths, according to the American Academy of Pediatrics