1. School of Sociology and Anthropology, Sun Yat-sen University, Guangzhou, P.R. China
2. Department of Medical Statistics & Epidemiology, School of Public Health, Sun Yat-sen University, Guangzhou, P.R. China
3. Sun Yat-sen Global Health Institute, School of Public Health and Institute of State Governance, Sun Yat-sen University, Guangzhou, P.R. China
4. Division of Primary Health Care, Guangzhou Center for Disease Control and Prevention, P.R. China
5. School of Health Management, Southern Medical University, Guangzhou, P.R. China