Funding for this research was provided by:
National Natural Science Foundation of China (81772144)
the Chinese State Key Project Specialized for Infectious Diseases (2018ZX10732401-001-008, 2018ZX10711001-003, 2018ZX10712001-015)
Received: 20 May 2019
Accepted: 30 October 2020
First Online: 10 November 2020
Ethics approval and consent to participate
: The study was approved by the Fifth Medical Centre, Chinese PLA General Hospital and the Center for Disease Control and Prevention of Shunyi District in Beijing, China. Written informed consent was obtained from each patient or a guardian.
: Not applicable. The manuscript does not contain personal details.
: The authors declare that they have no competing interests.