Published on in Vol 6, No 9 (2018): September
1 Department of Biostatistics and Epidemiology, School of Public Health, Sun Yat-sen University, Guangzhou, China
2 Sun Yat-sen Center for Migrant Health Policy, Sun Yat-sen University, Guangzhou, China
3 Sun Yat-sen Global Health Institute, Institute of State Governance, Sun Yat-sen University, Guangzhou, China
4 Department of Health Promotion and Community Health Sciences, School of Public Health, Texas A&M University, College Station, TX, United States
5 Department of Infectious Disease, Eighth People's Hospital, Guangzhou, China
*these authors contributed equally