1. The George Institute for Global Health, Beijing 100600, China
2. The George Institute for Global Health, Faculty of Medicine, University of New South Wales, Sydney, NSW 2052, Australia
3. School of Public Health, Anhui Medical University, Hefei 230032, China
4. Chinese Center for Health Education, Beijing 100011, China
5. Wolfson Institute of Population Health, Barts and The London School of Medicine & Dentistry, Queen Mary University of London, London E1 4NS, UK