1. Perelman School of Medicine at the University of Pennsylvania, Department of Medicine, Division of Infectious Diseases, 502 Johnson Pavilion, 3610 Hamilton Walk, Philadelphia, PA 19104-60732, USA
2. Botswana–UPenn Partnership, University of Botswana, Main Campus, 244G – Room 103, Gaborone, Botswana
3. Perelman School of Medicine at the University of Pennsylvania, Department of Biostatistics & Epidemiology, Center for Clinical Epidemiology & Biostatistics, Philadelphia, PA 19104, USA