Received: 4 February 2021
Accepted: 18 July 2021
First Online: 25 August 2021
: The collection of all NPA samples was approved by the ethics committee of the sixth people’s hospital of Nantong. An informed consent was obtained from all subjects including minors (participants aged less than 18) who was obtained from parents or legal guardians.
: Not applicable.
: The authors declare that they have no conflicts of interest.