1 State Key Laboratory for Communicable Diseases Prevention and Control, Chinese Center for Disease Control and Prevention, Beijing 102206, China.
2 State Key Laboratory for Communicable Diseases Prevention and Control, Chinese Center for Disease Control and Prevention, Beijing 102206, China. Email: lixianping@icdc.cn.
3 State Key Laboratory for Communicable Diseases Prevention and Control, Chinese Center for Disease Control and Prevention, Beijing 102206, China. Email: lujinxing@icdc.cn.