1 The Aurum Institute, Parktown, Johannesburg, South Africa 2193; School of Public Health, University of the Witwatersrand, Johannesburg, South Africa.
2 The Aurum Institute, Parktown, Johannesburg, South Africa 2193; School of Public Health, University of the Witwatersrand, Johannesburg, South Africa; Yale School of Public Health, Division of Epidemiology of Microbial Diseases, New Haven, CT, USA. Electronic address: scharalambous@auruminstitute.org.