Funding for this research was provided by:
National Science and Technology Major Project (2018ZX10101002-004-003)
National Natural Science Foundation of China (81773447, 81871694, 81561128006)
National Major Project of the State Key Laboratory of Infectious Diseases Prevention and Control (2011SKLID102)
Received: 19 September 2020
Accepted: 12 January 2021
First Online: 21 January 2021
Ethics approval and consent to participate
: The ethical review of this study was formally approved by and obtained written consent (approval no. X190111549) from the Medical Ethics Certification Committee of the Chinese Center for Disease Control and Prevention. Written informed consent was obtained from all subjects included in the study.
: Not applicable.
: The authors report no conflicts of interest in this work.