1. Clinical Trial Service Unit and Epidemiological Studies Unit (CTSU), Nuffield Department of Population HealthUniversity of Oxford Oxford UK
2. Medical Research Council Population Health Research Unit (MRC PHRU), Nuffield Department of Population HealthUniversity of Oxford Oxford UK
3. Chinese Academy of Medical Sciences Beijing China
4. Jiangsu CDC Jiangsu China
5. Meilan CDC Hainan China
6. Department of Epidemiology and Biostatistics, School of Public HealthPeking University Beijing China