Funding for this research was provided by:
National Natural Science Foundation of China (81371866)
National Grant Program on Key Infectious Diseases (2014ZX10002002-002)
Received: 26 January 2017
Accepted: 18 June 2018
First Online: 3 July 2018
Ethics approval and consent to participate
: The study was approved by the Ethical Committee of the Third Affiliated Hospital of the Sun Yat-sen University, which waived the need for informed consent because all the data used in this retrospective study were routinely obtained and no additional procedures were carried out.
: Not applicable.
: The authors declare that they have no competing interests.
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