In this Jan. 8, 2021, file photo, a pharmacist prepares a syringe of the Pfizer vaccine for COVID-19, at Queen Anne Healthcare, a skilled nursing and rehabilitation facility in Seattle. The U.S. vaccination drive against COVID-19 stood on the verge of a major new phase as government advisers Thursday, Sept. 23, recommended booster doses of Pfizer’s vaccine for millions of older or otherwise vulnerable Americans — despite doubts the extra shots will do much to slow the pandemic. (AP Photo/Ted S. Warren, File)