Funding for this research was provided by:
Medical Health Science and Technology Project of Zhejiang Province, China (2019KY052, 2021KY118)
Zhejiang Province Public Welfare Technology Application Research Project (2019KY059)
National Natural Science Foundation of China (81973106)
Beijing Municipal Natural Science Foundation (19L2060)
Received: 21 May 2021
Accepted: 21 August 2021
First Online: 30 August 2021
: The study protocol was approved by the ethics committee of the Chinese Centre for Disease Control and Prevention (ICDC-2019010) before study initiation. Written informed consent was obtained from all study participants or their guardian/parents prior to inclusion in the study. In order to protect participants’ confidentiality, the data was guarded by a person and exported without participants’ name or informed consent form.
: Not applicable.
: All authors declare that they have no conflicts of interest.