Funding for this research was provided by:
National key research and development plan of China (2016TFC1202700, 2016YFC1200903, 2017YFC1200503)
China Mega-Project for Infectious Disease (2017ZX10302301-004)
China Mega-Project for Infectious Disease (2017ZX10104001)
Received: 1 February 2018
Accepted: 11 April 2018
First Online: 2 May 2018
Ethics approval and consent to participate
: All aspects of the study were performed in accordance with national ethics regulations and approved by the Institutional Review Boards of National Institute for Viral Disease Control and Prevention, Center for Disease Control and Prevention of China and the Ethics Committee of Children’s hospital of Hebei Province, china.
: The authors declare that they have no competing interests.
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