Funding for this research was provided by:
the National key R&D Program of China (2018YFC2002000 & 2018YFC2002001)
Received: 6 December 2019
Accepted: 23 March 2020
First Online: 10 April 2020
Ethics approval and consent to participate
: The Research Ethics Committee of the Division for the Prevention and Control of Chronic Non-communicable Diseases, China Center for Disease Control and Prevention, approved the study protocol.
: Not applicable.
: The authors declare no competing interests.