1. Department of Epidemiology, School of Public Health, Southern Medical University, Guangzhou 510515, China
2. Institute of Pathogenic Microbiology, Guangdong Provincial Center for Disease Control and Prevention, Guangdong Workstation for Emerging Infectious Disease Control and Prevention, Chinese Academy of Medical Sciences, Guangzhou 511430, China
3. Department of Infectious Diseases, Nanfang Hospital, Southern Medical University, Guangzhou 510515, China