Fig. 1.

An overview of point-of-care detection methods for COVID-19. (a) Diagrammatic expression of SARS-CoV-2: a single stranded viral RNA with three surface proteins, including Spike (S), Envelop (E), and Membrane (M). (b) Real samples collected for COVID-19 detection: throat swab for virus detection and blood samples for antibody detection; (c) An overview of RNA detection methods, including reverse transcription polymerase chain reaction (RT-PCR), isothermal amplification methods and clustered regularly interspaced short palindromic repeats (CRISPR)-based methods [7]; Reproduced with permission. Copyright 2020, BioRxiv. (d) Schematic illustration of concentrations of the IgG and IgM antibodies in individuals once infected with SARS-CoV-2: IgM antibodies are first to appear in serum samples and are detectable as early as 3 days after infection. The concentration of IgM peaks between 2 and 3 weeks. IgG antibodies come after IgM but last longer. They peak after 2 weeks [49]; (e) Schematic detection mechanisms of IgG and IgM based on lateral flow immunoassays and enzyme-linked immunosorbent assays.