Funding for this research was provided by:
Guangdong Science and Technology Department (2018B020241002, 2018B020207013)
National Major Science and Technology Projects of China (2018ZX10101002)
Received: 1 February 2020
Accepted: 13 May 2020
First Online: 24 May 2020
Ethics approval and consent to participate
: No patient involved. In this study, all data was obtained from government websites and public data sets of the CDC, etc., which removed the patient identifiers. There was no direct patient and public involvement.
: This study was a retrospective study, it did not contain any individual person’s data.
: Author Wenbiao Hu is an Editorial Board Member.