Justin Lessler*, Derek A. T. Cummings, Steven Fishman, Amit Vora and Donald S. Burke Johns Hopkins Bloomberg School of Public Health, 615 North Wolfe Street E5537, Baltimore, MD 21205, USA Department of Epidemiology, Graduate School of Public Health, University of Pittsburgh, 130 DeSoto Street, Pittsburgh, PA 15261, USA Department of Biostatistics, Johns Hopkins Bloomberg School of Public Healt...
