1. Department of Infectious Diseases, 940th Hospital of Joint Logistics Support Force of the Chinese People's Liberation Army , Lanzhou , China
2. Department of Epidemiology, Ministry of Education Key Lab of Hazard Assessment and Control in Special Operational Environment, School of Public Health, Air Force Medical University , Xi’an , China
3. Department of Immunization Program, Wuwei Municipal Center for Disease Control and Prevention , Wuwei , China
4. Department of Infectious Diseases, Wuwei People's Hospital , Wuwei , China
5. Department of Hygienic Logistics, 940th Hospital of Joint Logistic Support Force of the Chinese People's Liberation Army , Lanzhou , China