Text and Data Mining valid from 2019-06-12
Received: 7 December 2018
Accepted: 30 May 2019
First Online: 12 June 2019
Compliance with Ethical Standards
: The authors declare that they have no conflict of interests.
: All procedures performed in studies involving human participants were in accordance with the ethical standards of the Ethical Review Committee of Fujian Municipal Center for Disease Control and Prevention and with the 1964 Helsinki Declaration and its later amendments or comparable ethical standards. Informed consent was obtained from all participants enrolled in the study.