1 Public Health Modeling Unit and Department of Epidemiology of Microbial Diseases, Yale School of Public Health, New Haven, CT.
2 Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina at Chapel Hill, Chapel Hill, NC.
3 Departments of Pediatrics and Epidemiology, Biostatistics and Occupational Health, McGill University, Montreal, QC, Canada.
4 Epidemiology Branch, Division of Intramural Population Health Research, Eunice Kennedy Shriver National Institute of Child Health and Human Development, Bethesda, MD.