Funding for this research was provided by:
China-UK Global Health Support Programme (Not applicable)
Received: 20 May 2019
Accepted: 5 August 2019
First Online: 30 August 2019
Ethics approval and consent to participate
: This study obtained ethical approval from the Medical Research Ethics Committee, School of Public Health, Fudan University (IRB00002408&FWA00002399). All participants were asked to provide verbal informed consent after being read a document emphasizing the voluntary nature of the survey.
: All authors consented to have the paper published.
: The authors declare there are no competing interests.