From the Center for Communicable Disease Dynamics, Department of Epidemiology, Harvard T.H. Chan School of Public Health, Boston (M.L.); Medical Development and Scientific/Clinical Affairs, Pfizer Vaccines, Collegeville, PA (D.L.S.); and the Center for Observational and Real-World Evidence, Merck, Kenilworth, NJ (L.F.). (2020-03-26時点)