1. Department of Epidemiology and Statistics, School of Public Health, Anhui Medical University, Hefei, Anhui, China
2. Center for Disease Control and Prevention of Hefei City, Hefei, China
3. Department of Maternal, Child and Adolescent Health, School of Public Health, Anhui Medical University, Hefei, Anhui, China
4. Discipline of Public Health, the University of Adelaide, Adelaide, SA, Australia