2 Department of Epidemiology, University of Washington School of Public Health, Seattle, Washington, USA.
3 Welcome Centre for Infectious Diseases Research in Africa, Infectious Disease and Molecular Medicine Unit and Department of Medicine, University of Cape Town, Cape Town, South Africa.
4 Botswana National Health Laboratory, Gaborone, Botswana.
5 Centre for Global Health, Institute for Infection and Immunity, St. George's University of London, UK.
6 Botswana Harvard AIDS Institute Partnership, Gaborone, Botswana.
7 Department of Clinical Research, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, UK.