Published on in Vol 22 , No 5 (2020) :May
Preprints (earlier versions) of this paper are
available at
https://preprints.jmir.org/preprint/18718, first published
.

1 Zhejiang Provincial Center for Disease Control and Prevention, Hangzhou, CN
2 Jiashan Prefectural Center for Disease Control and Prevention, Jiashan, CN
*these authors contributed equally