Funding for this research was provided by:
The National Key Research and Development Program of China (2016YFE0201500)
The Innovation Project of Shandong Academy of Medical Sciences (No)
The Syphilis and Other Sexually Transmitted Diseases Control Research in Shandong (No)
Text and Data Mining valid from 2019-05-06
Received: 23 December 2018
Accepted: 15 April 2019
First Online: 6 May 2019
Ethics approval and consent to participate
: This study was conducted in conformity to the ethical principles stated in the Helsinki Declaration. This study was reviewed and approved by the Ethics Committee of Shandong Provincial Institute of Dermatology and Venereology (approval number: 2016–04). The topic of the questionnaires was related to sex. Participants may refuse to answer sensitive questions or provide untruthful information if they signed informed consent. In order to obtain accurate information, oral informed consent instead of written consent was obtained from participants before each interview. This procedure was approved by the ethics committee.
: Not applicable.
: The authors declare that they have no competing interests.
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