1. Division of Infectious Disease, Key Laboratory of Surveillance and Early-warning on Infectious Disease, Chinese Center for Disease Control and Prevention (China CDC), Beijing, China
2. These authors contributed equally to this work
3. School of Public Health, Li Ka Shing Faculty of Medicine, University of Hong Kong, Hong Kong Special Administrative Region, China
4. Jiangxi Provincial Centre for Disease Control and Prevention, Nanchang, Jiangxi Province, China
5. Beijing Center for Disease Prevention and Control; and Beijing Research Center for Preventive Medicine, Beijing, China
6. Office of Director-General, Chinese Center for Disease Control and Prevention (China CDC), Beijing, China
7. CAS Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China