Funding for this research was provided by:
Key Technologies Research and Development Program (2018ZX10305410-003-002, 2017ZX10104001, 2018ZX10713002)
Received: 14 October 2020
Accepted: 8 February 2021
First Online: 18 February 2021
Ethics approval and consent to participate
: The project was approved by the Ethical Committee of National Institute for Viral Disease Control and Prevention, China CDC, and the committee's reference number is IVDC2018-012.
: Written informed consent for specimen collection, testing and publication was obtained from all individuals (or their parents) in the study population.
: The authors declare that they have no competing interests.