Lu, Ying
Ma, Mengmeng
Wang, Hui
Wang, Dahu
Chen, Chun
Jing, Qinlong
Geng, Jinmei
Li, Tiegang
Zhang, Zhoubin
Yang, Zhicong
Article History
Received: 17 June 2019
Accepted: 22 December 2019
First Online: 8 January 2020
Ethics approval and consent to participate
: This study was approved by the Ethics Committee of Guangzhou Center for Disease Control and prevention (GZCDC), and written informed consent was obtained from all participants.
: Not applicable.
: The authors declare that they have no competing interests.