1. Hebei Center for Disease Control and Prevention, Shijiazhuang, China.
2. Department of Epidemiology and Health Statistics, School of Public Health, Central South University, Changsha, China.
3. Shijiazhuang Center for Disease Control and Prevention, Shijiazhuang, China.
4. Liaocheng Center for Disease Control and Prevention, Liaocheng, China.
5. Xiangya Medical School, Central South University, Changsha, China.