Article History
Received: 18 March 2020
Accepted: 5 August 2020
First Online: 14 September 2020
Compliance with Ethical Standards
:
: The authors declare that they have no conflict of interest.
: This study was approved by the Ethics Committee of Qinghai Center for Disease Control and Prevention, the related procedures were performed according to the guideline of National Influenza Surveillance Program (Edition 2017).