Funding for this research was provided by:
the Youth Science Fund Project of the National Science Foundation of China (71603167)
Received: 8 May 2019
Accepted: 28 January 2020
First Online: 6 February 2020
Ethics approval and consent to participate
: The study protocol was approved by the Ethics Committee of School of Public Health, Shanghai Jiaotong University (Approval No.2016012). All participants gave informed written consent prior to the study.
: Not applicable.
: The authors declare that they have no competing interests.