1. London School of Hygiene & Tropical Medicine, London, UK, and, Université Montpellier 1, EA 4205, Transmission, Pathogenese et Prevention de l’Infection par le VIH, and, CHU Montpellier, Montpellier, France.
2. London School of Hygiene & Tropical Medicine, London, UK and, Reproductive Health & HIV Research Unit, University of the Witwatersrand, Johannesburg, South Africa.
3. London School of Hygiene & Tropical Medicine, Clinical Research Unit, Department of Infectious & Tropical Diseases, London WC1E 7HT, UK.