1. Department of Epidemiology and Biostatistics School of Public Health Peking University Beijing China
2. Qingdao Center for Disease Control and Prevention Qingdao China
3. Zhejiang Center for Disease Control and Prevention Hangzhou China
4. Jiangsu Center for Disease Control and Prevention Nanjing China
5. Sichuan Center for Disease Control and Prevention Chengdu China
6. Beijing Center for Disease Control and Prevention Beijing China
7. Shanghai Center for Disease Control and Prevention Shanghai China
8. Tianjin Center for Disease Control and Prevention Tianjin China
9. Qinghai Center for Disease Control and Prevention Xining China
10. Heilongjiang Center for Disease Control and Prevention Harbin China
11. Handan Center for Disease Control and Prevention Handan China
12. Yunnan Center for Disease Control and Prevention Kunming China