Funding for this research was provided by:
National Key R & D Program of China (2017 YFC 0907001)
Received: 23 March 2019
Accepted: 24 July 2019
First Online: 2 August 2019
Ethics approval and consent to participate
: Our study did not involve any health-related human participants interventions. The study protocol conforms to the ethical guidelines of the 1975 Declaration of Helsinki and approved by the ethical review committee of School of Public Health, Fudan University (IRB approval number 2016-04-0586). Written informed consent was obtained from all study participants prior to the study.
: Not Applicable.
: The authors declare that they have no competing interests.