1. Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland (J.A.C., J.A., J.E.R., S.H.M.)
2. Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, and Division of Infectious Diseases, Johns Hopkins School of Medicine, Baltimore, Maryland (D.L.T., G.D.K.)
3. School of Nursing, University of Wisconsin, Madison, Wisconsin (R.G.).