1. Ezintsha, Faculty of Health Sciences, University of the Witwatersrand , Johannesburg 2193 , South Africa
2. Medical Practice Evaluation Center, Massachusetts General Hospital and Harvard Medical School , Boston, MA 02115 , USA
3. Division of Infectious Diseases and Department of Global Health, Emory University School of Medicine and Rollins School of Public Health , Atlanta, GA 4223 , USA
4. Department of Pharmacology and Therapeutics, University of Liverpool , Liverpool L69 7BE , UK
5. Hubert Department of Global Health, Rollins School of Public Health, Emory University , Atlanta, GA 4223 , USA
6. Department of Family and Preventive Medicine, School of Medicine, Emory University , Atlanta, GA 30322 , USA
7. Department of Medicine, University College London , London WC1E 6BT , UK
8. Department of Public Health Medicine, Faculty of Health Sciences, School of Health Systems and Public Health, University of Pretoria , Pretoria 0028 , South Africa