Comparison and application of different immunoassay methods for the detection of SARS-CoV-2

The detection data of IgM and IgG antibodies in 169 patients with coronavirus disease-2019 (COVID-19) were analyzed to evaluate differences in clinical performance between the colloidal gold method and chemiluminescence method. In this study, chemiluminescence detection of IgM antibody showed a positive conversion earlier (about 1-2 days earlier), positive conversion rates higher in different stages of disease, and a trend of declining positive rate later than colloidal gold method. For IgG antibody, the chemiluminescence method showed a positive conversion earlier and the positive rate climbing more quickly than the colloidal gold method. No obvious negative-converting tendency of IgG detection was observed within 35 days after the onset of disease. Although colloidal gold method is generally less sensitive than chemiluminescence method, it shows advantages of shorter turn-around time, more simple procedure, and no special equipment required. The two methodologies can be chosen according to different laboratory conditions. A reasonable understanding of the performance of reagents with different methodologies can help in clinical disease diagnosis effectively and assist in the diagnosis of the progression of COVID-19, for which the dynamic changes of antibody will provide reliable evidence.