FILE PHOTO: U.S. President Donald Trump is flanked by Health and Human Services (HHS) Secretary Alex Azar and National Institutes of Health Doctor Kizzmekia Corbett, research fellow at the NIH Vaccine Research Center, as he listens to Director of National Institute of Allergy and Infectious Diseases Anthony Fauci following a briefing at the Vaccine Research Center in Bethesda, Maryland, U.S., March 3, 2020. REUTERS/Leah Millis