Source tracing of the COVID-19 infection case in Guangxi, China

ABSTRACT

The study describing the process of discovery and source tracing of a native case of coronavirus disease 2019 (COVID-19) infection on Jan 2021, in Guangxi, China, to provide methodology for source investigation better in the future. Following the Epidemiological Investigation Plan for COVID-19 (version 7), information of the native COVID-19 case and related close contacts were collected. Real time reverse transcription-quantitative polymerase chain reaction was performed to detect the nucleic acids of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) in samples collected from the infection case, related close contacts, and the environment, combined with serum specific antibody detection. The positive nucleic acid samples were undergone whole genome sequencing, phylogenetic analysis and analyses of variation of amino acids. The whole genome sequence from the native case and the imported asymptomatic infected case from Indonesia containing 25 nucleotide mutation sites belong to L-Lineage European Branch II. 3. The imported asymptomatic case was the source of infection of this native case. The possible route of infection was that native case was exposed to contaminated environment by imported case, due to improper personal protective equipment. A focus on local outbreaks of COVID-19 caused by SARS-CoV-2-infected people from outside China is needed.