1. Department of Internal Medicine, Faculty of Medicine, University of Botswana, Gaborone Private Bag 00713, Botswana
2. Bennett Statistical Consulting, Inc., Ballston Lake, NY 12019, USA
3. Botswana-Harvard Health Partnership, Gaborone Private Bag BO 320, Botswana
4. Department of Immunology & Infectious Diseases, Harvard T. H. Chan School of Public Health, Boston, MA 02115, USA
5. Division of Infectious Diseases, Brigham & Women’s Hospital, Boston, MA 02115, USA