A nurse prepares a shot of the Pfizer-BioNTech COVID-19 vaccine at Guy’s Hospital in London, Tu …

A nurse prepares a shot of the Pfizer-BioNTech COVID-19 vaccine at Guy's Hospital in London, Tu ...

A nurse prepares a shot of the Pfizer-BioNTech COVID-19 vaccine at Guy’s Hospital in London, Tuesday, Dec. 8, 2020, as the U.K. health authorities rolled out a national mass vaccination program. (AP Photo/Frank Augstein)