1. Medical Research Council/Uganda Virus Research Institute and London School of Hygiene and Tropical Medicine, Uganda Research Unit, PO Box 49, Entebbe, Uganda
2. African Population and Health Research Center, P.O. Box 10787-00100, Kitisuru, Nairobi, Kenya
3. Joint Clinical Research Centre, PO Box 10005, Kampala, Uganda
4. University of Zurich, Epidemiology, Biostatistics and Prevention Institute, CH 8001, Zurich, Switzerland
5. Infectious Diseases Institute, Makerere University, PO Box 22418, Kampala, Uganda
6. Medical Research Council, Clinical Trials Unit at University College London, London WC1V 6LH, UK
7. Global Health and Development Department, London School of Hygiene & Tropical Medicine, London, WC1E 7HT, UK