University of the Witwatersrand - MRC/Wits Rural Public Health and Health Transitions Research Unit, University of the Witwatersrand - MRC/Wits Rural Public Health and Health Transitions Research Unit, University of the Witwatersrand - MRC/Wits Rural Public Health and Health Transitions Research Unit, University of North Carolina (UNC) at Chapel Hill - Department of Epidemiology, University of North Carolina (UNC) at Chapel Hill - Carolina Population Center, University of Edinburgh - College of Medicine & Veterinary Medicine, University of Edinburgh - College of Medicine & Veterinary Medicine, National Health Laboratory Services (NHLS) - Centre for Respiratory Diseases and Meningitis, University of the Witwatersrand - MRC/Wits Rural Public Health and Health Transitions Research Unit and University of the Witwatersrand - MRC/Wits Rural Public Health and Health Transitions Research Unit