Xu, Lizheng
Guo, Min
Nicholas, Stephen
Sun, Long
Yang, Fan
Wang, Jian http://orcid.org/0000-0001-9539-2016
Funding for this research was provided by:
National Natural Science Foundation of China (71373146, 71603136, 71702131)
Article History
Received: 12 August 2019
Accepted: 6 January 2020
First Online: 14 January 2020
Ethics approval and consent to participate
: The project was approved by the Public Health Ethics Committee at Shandong University School of Public Health (Grant No. 20190406). Written informed consent was obtained from all participants prior to research. Participants were informed that they could refuse to answer any question. The questionnaire did not ask about infection status, and no biological samples were collected.
: Not applicable.
: The authors declare that they have no competing interests.