Funding for this research was provided by:
National Basic Research Program of China (973 Program) (2018YFC1200100&2018YFC1200102)
Beijing Municipal Science&Technology COmmission PR China (Z171100001017118)
Text and Data Mining valid from 2019-09-09
Received: 18 April 2019
Accepted: 27 August 2019
First Online: 9 September 2019
Ethics approval and consent to participate
: The institutional review boards at the Henan provincial people’s hospital approved the study protocol. The written informed consent from participants was exempted, because it focused only on the epidemical features of SGSP strains, and the privacy of involved subjects was not affected.
: Not applicable.
: I confirm that I have read BioMed Central’s guidance on competing interests. The authors declare that they have no competing interests.