FILE - A healthcare worker holds a vial of the Pfizer COVID-19 vaccine at Jackson Memorial Hospital in Miami, in this Tuesday, Oct. 5, 2021, file photo. Pfizer asked the U.S. government Thursday, Oct. 7, 2021, to allow use of its COVID-19 vaccine in children ages 5 to 11 -- and if regulators agree, shots could begin within a matter of weeks. (AP Photo/Lynne Sladky, File)