Vaccine trial participant David Rach is prepared to test coronavirus disease (COVID-19) vaccine candidate BNT162b2, developed by Pfizer and BioNTech, at the Center for Vaccine Development and Global Health at the University of Maryland School of Medicine in Baltimore, Maryland, U.S. in a still image from video taken May 24, 2020. Video taken May 24, 2020. Pfizer/Handout via REUTERS. NO RESALES. NO ARCHIVES. THIS IMAGE HAS BEEN SUPPLIED BY A THIRD PARTY.