The US Food and Drug Adminstration on Friday granted the Pfizer-BioNTech Covid-19 vaccine an emergency use authorization, paving the way for its imminent rollout across the country. "I am authorizing the emergency use of Pfizer-BioNTech COVID?19 Vaccine for the prevention of COVID-19," Denise Hinton, the agency's chief scientist wrote in a letter to a Pfizer executive. ia/st