University of California, Los Angeles (UCLA) - Department of Epidemiology, affiliation not provided to SSRN, University of Colorado, Aurora - Anschutz Medical Campus, University of Cape Town - Division of Clinical Pharmacology, affiliation not provided to SSRN, University of Cape Town (UCT) - Division of Epidemiology & Biostatistics, affiliation not provided to SSRN, University of Cape Town (UCT) - Centre of Infectious Disease Epidemiology and Research (CIDER), University of Cape Town (UCT) - Desmond Tutu HIV Centre, affiliation not provided to SSRN, University of California, Los Angeles (UCLA) - Department of Epidemiology and University of Cape Town (UCT) - Division of Epidemiology & Biostatistics