Chen, Wei
Ren, Hongfu
Wang, Na
Xiong, Yaqing
Xu, Fei
Article History
Received: 10 January 2021
Accepted: 9 March 2021
First Online: 17 March 2021
Declarations
:
: The Academic and Ethical Committee of Nanjing Municipal Center for Disease Control and Prevention approved this study. All methods were carried out in accordance with relevant guidelines and regulations. Written informed consent was obtained from each participant.
: Not applicable.
: Prof. Fei Xu is an Editorial Board member of BMC Public Health. No other competing interests exist.