Funding for this research was provided by:
National Natural Science Foundation of China (11661026, 81773497)
Natural Science Foundation of Guangdong Province (2017A030313699)
Guangdong Medical Research Foundation (A2017474)
Natural Science Foundation of Guangxi Province (2017GXNSFAA198235)
the National Key R\&D Program of Ministry of Science and Technology of China (No. 2018YFB0505500 and 2018YFB0505503)
Received: 16 May 2018
Accepted: 24 April 2019
First Online: 4 June 2019
Ethics approval and consent to participate
: The present study was fully reviewed and approved by the Ethics Committee of Guangdong Provincial Center for Disease Control and Prevention. All the patient data were de-identified and the data were analysed anonymously.
: Not applicable.
: The authors declare that they have no competing interests.
: Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.