University of the Witwatersrand - Reproductive Health and HIV Research Unit (RHRU), affiliation not provided to SSRN, Chris Hani Baragwanath Academic Hospital - Perinatal HIV Research Unit, New York University (NYU), Johns Hopkins University - Bloomberg School of Public Health, affiliation not provided to SSRN, Seoul National University, Johns Hopkins University, New York University (NYU) - New York University, Chris Hani Baragwanath Academic Hospital - Perinatal HIV Research Unit, University of the Witwatersrand, University of the Witwatersrand, University of the Witwatersrand - Perinatal HIV Research Unit, Johns Hopkins University and affiliation not provided to SSRN