1. Department of Obstetrics and Gynecology, School of Medicine and Duke Global Health Institute; Duke University; Durham; NC; USA
2. Department of Epidemiology; Gillings School of Global Public Health; Chapel Hill; NC; USA
3. Department of Epidemiology; Harvard School of Public Health; Boston; MA; USA
4. Division of Infectious Diseases; Northwestern University Feinberg School of Medicine; Chicago; IL; USA
5. Department of Infectious Diseases and Microbiology; University of Pittsburgh; Pittsburgh; PA; USA
6. Department of Epidemiology; Johns Hopkins Bloomberg School of Public Health; Baltimore; MD; USA