Clinical Utility of SARS-CoV-2 Antibody Testing

Abstract

SARS-CoV-2 antibody assay is a test that checks whether an antibody against the SARS-CoV-2 virus has been formed in the blood after SARS-CoV-2 infection or vaccination. SARS-CoV-2 antibody is detected 1–2 weeks after infection, and antibodies are produced in more than 90% of infected patients. The duration for the formation of antibodies differs by individual and by type of antibody. In the case of IgG, it is at least several months or longer, and the relationship between antibodies and immunity is being studied. As test methods,enzyme-linked immunosorbent assay (ELISA), chemiluminescence immunoassay (CIA), immunochromatographic assay, and neutralizing antibody assay have been developed and used. The target antibody to be detected differs depending on the type of recombinant antigen and the type of secondary antibody in reagents. Many kinds of commercialized SARS-CoV-2 antibody assays are currently being developed, and the S (spike) protein, N (nucleocapsid) protein, S1 or RBD (receptor binding domain) part of the S protein, and a mixture of these antigens are used as recombinant antigens of reagents. IgG, IgM, IgA, or total immunoglobulin antibodies in patients’ blood that react with these reagent antigens are detected. In this review, the types and performance of SARS-CoV-2 antibody tests and the guidelines for COVID-19 antibody tests published domestically and abroad were investigated.