Pfizer Inc. /zigman2/quotes/202877789/composite PFE -0.02% and German partner BioNTech SE /zigman2/quotes/214419716/composite BNTX +5.96% said Tuesday they have submitted initial data from the late-stage trial of their COVID-19 vaccine in children aged 5 to 12 to the U.S. Food and Drug Administration, and are seeking an emergency-use authorization to add that patient group to the program. The news comes after the companies released initial data from the trial last week, saying the vaccine had proved safe and effective. The companies used two doses of just 10 mg in a trial involving 2,268 participants. "Topline immunogenicity and safety readouts for the other two age cohorts from the trial -- children 2 to <5 years of age and children 6 months to <2 years of age -- are expected as soon as the fourth quarter of this year," the companies said in a statement. They are also planning to submit data from the full Phase 3 trial for scientific peer-reviewed publication. Pfizer shares were down 0.6% premarket, while BioNTech was down 3%.