1 Guangdong Provincial Center for Disease Control and Prevention, Guangzhou, China; WHO Collaborating Centre for Surveillance, Research and Training of Emerging Infectious Diseases, Guangzhou, China.
2 Guangdong Provincial Center for Disease Control and Prevention, Guangzhou, China; WHO Collaborating Centre for Surveillance, Research and Training of Emerging Infectious Diseases, Guangzhou, China. Electronic address: [email protected].
3 Erasmus MC, Department of Viroscience, Rotterdam, The Netherlands.
4 Chinese Center for Disease Control and Prevention, China.