Funding for this research was provided by:
National Natural Science Foundation of China (No.81601794)
Jiangsu Provincial Key Medical Discipline of Epidemiology (ZDXKA2016008)
Jiangsu Provincial Medical & Youth Talent (No. ZDRCA2016032, No.QNRC2016545)
Received: 18 March 2019
Accepted: 28 January 2020
First Online: 4 February 2020
Ethics approval and consent to participate
: Ethics Committee of the Jiangsu Provincial Center for Disease Control and Prevention approved the application for informed consent to exempt signature, and reference number was JSCDCLL函字 006.The trained investigators explained and informed the respondents orally in an easy-to-understand language detailing the background, purpose, method, rights and obligations, and expected benefits of the study. The respondents were clear about their right to withdraw at any time without giving reasons.The investigators ensured that each respondent fully understood the content of the study and volunteered to complete the survey. The survey started after obtaining the oral informed consent of the respondents. Meanwhile, all data were anonymous.
: Not applicable.
: The authors declare that they have no competing interests.