1. Harvard Center for Population and Development Studies, Harvard T.H. Chan School of Public Health, Cambridge , Massachusetts, United States
2. MRC/Wits Rural Public Health and Health Transitions Research Unit (Agincourt), School of Public Health, Faculty of Health Sciences , University of the Witwatersrand, Johannesburg, Gauteng, South Africa
3. Department of Preventive Medicine, Yonsei University College of Medicine , Seoul, South Korea
4. Heilbrunn Department of Population and Family Health, Mailman School of Public Health, Columbia University , New York City, New York, United States