Pfizer Inc. /zigman2/quotes/202877789/composite PFE -2.33% and German partner BioNTech SE /zigman2/quotes/214419716/composite BNTX -5.77% said Thursday the U.S. government has purchased an additional 50 million pediatric doses of their COVID-19 vaccine, as it prepares to start dosing children. The additional order includes vaccines for children below the age of 5, assuming they will receive regulatory authorization. The new doses are expected to be delivered by April 30 of 2022. The order marks the final purchase option for the government under its existing supply agreement with the companies, bringing the total number of doses secured to 600 million, including doses for adults and adolescents. "Separately, Pfizer and BioNTech have agreed to provide a total of 1 billion doses to the U.S. government at a not-for-profit price for donation to low- and lower-middle-income countries," the companies said in a joint statement. Earlier this week, an FDA advisory committee recommended dosing children aged 5 to 11. The FDA has yet to weigh in on that vote, and the CDC will meet next week to make the final decision. Both stocks were higher premarket.