1. Tongzhou District Center for Disease Control and Prevention, Beijing, China.
2. State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Academy of Military Medical Sciences, Beijing, China.
3. School of Public Health, Gannan Medical University, Ganzhou, China.
4. School of Public Health, North China University of Science and Technology, Tangshan, China.
5. West China Hospital, State Key Laboratory of Biotherapy and Cancer Center, Sichuan University, Chengdu, China.