1. Guangdong Provincial Center for Disease Control and Prevention, Guangdong Workstation for Emerging Infectious Disease Control and Prevention, Panyu District, Guangzhou, China
2. School of Public Health, Southern Medical University, Baiyun District, Guangzhou, China
3. WHO WPRO Regional Polio Reference Laboratory and Ministry of Health Key Laboratory for Medical Virology, National Institute for Viral Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Changping District, Beijing, China
4. Department of Virology II, National Institute of Infectious Diseases, Tokyo, Japan