Received: 4 February 2021
Accepted: 25 May 2021
First Online: 29 June 2021
: The study was conducted according to the guidelines of the Declaration of Helsinki. The study protocols were approved by the Institutional Review Boards of Nantong University and the Nantong Centers for Disease Control. All participants provided written informed consent.
: Not applicable.
: No conflicts of interest, financial or otherwise, are declared by the authors.