From the Centers for Disease Control and Prevention COVID-19 Response Team, Atlanta (M.G.T., A.L.F., L.G., J.M.L., Y.M.Y., G.J., J. Mak, B.L., Y.Z., J.Z., A.K., Y.L., M.D., S.T., J.B., E.A.-B., M.L.A., P.K., A.M.F.); the Mel and Enid Zuckerman College of Public Health, University of Arizona, Tucson (J.L.B., K.L., K.E., X.S., J.G., S.B., P.R.); Kaiser Permanente Northwest Center for Health Research, Portland, OR (A.L.N., H.C.G., J.L.K.); the Whiteside Institute for Clinical Research (M.J.O.), St. Luke's Regional Health Care System (H.T., M.J.O.), Duluth, MN; University of Utah, Salt Lake City (S.K.Y., K.H., M.S.T., A.L.P., R.T.B.); the Marshfield Clinic Research Institute, Marshfield (J. Meece, E.S., L.I.), and the Wisconsin State Laboratory of Hygiene, Madison (E.H., K.G., A.B., E.R.) - both in Wisconsin; Abt Associates, Rockville, MD (L.E.W.O., L.J.E., M.G.W., K.D.G., M.K.H., T.C.M., B.P.P., D.R.H.); the Leonard M. Miller School of Medicine, University of Miami, Miami (A.J.C.-M., N.S.-S.); and Baylor Scott and White Health, Dallas (K.D., T.Z., M.E.S., M.G.), and Texas A&M University College of Medicine, Bryan (M.G.) - both in Texas.