[1] Malawi Liverpool Wellcome Trust Clin Res Programm, Blantyre, Malawi
[2] Imperial Coll London, Dept Infect Dis Epidemiol, London W2 1PG, England
[3] Univ Liverpool Liverpool Sch Trop Med, Dept Clin Sci, Liverpool, Merseyside, England
[4] Univ Liverpool, Dept Publ Hlth & Policy, Liverpool, Merseyside, England
[5] LSHTM, Infect Dis Epidemiol Dept, London, England
[6] Minist Hlth, Dept HIV AIDS, Lilongwe, Malawi
[7] LSHTM, Clin Res Dept, London, England