The first patient enrolled in Pfizer’s COVID-19 vaccine clinical trial at the University of Maryland School of Medicine in Baltimore receives an injection in May.

FILE – In this May 4, 2020 photo provided by the University of Maryland School of Medicine, the first patient enrolled in Pfizer’s COVID-19 coronavirus vaccine clinical trial at the University of Maryland School of Medicine in Baltimore, receives an injection. On top of rigorous final testing in tens of thousands of people, any COVID-19 vaccines cleared for widespread use will get additional safety evaluation as they’re rolled out. (University of Maryland School of Medicine via AP)