Funding for this research was provided by:
Bill and Melinda Gates Foundation (OPP1137180)
Article History
Received: 5 March 2021
Accepted: 17 March 2021
First Online: 25 March 2021
Declarations
:
: The study was approved by the Institutional Review Board of the Chinese Center for Disease Control and Prevention [201626].
: Not applicable.
: The authors declare that they have no competing interests.