1. Southern Medical University, Guangzhou, China
2. Shenzhen Exit-Entry Inspection and Quarantine Bureau, Shenzhen, China
3. National Institute for Communicable Disease Control and Prevention, Chinese CDC, Beijing, China
4. State Key Laboratory for Infectious Diseases Prevention and Control, Beijing, China
5. Guangdong Institute of Public Health, Guangzhou, China
6. Center for Disease Control and Prevention of Guangdong Province, Guangzhou, China