[1] Univ Cape Town, Div Med Virol, Dept Pathol, Cape Town, South Africa
[2] Univ Cape Town, Inst Infect Dis & Mol Med, Cape Town, South Africa
[3] Univ Cape Town, Inst Infect Dis & Mol Med, Clin Infect Dis Res Initiat, Cape Town, South Africa
[4] Univ Cape Town, Sch Publ Hlth & Family Med, Div Publ Hlth Med, Cape Town, South Africa
[5] Francis Crick Inst, Mill Hill Lab, London, England
[6] Imperial Coll London, Dept Med, London, England