Evaluation of nine commercial SARS-CoV-2 immunoassays

Ria Lassaunière; Anders Frische; Zitta B Harboe; Alex CY Nielsen; Anders Fomsgaard; Karen A Krogfelt; Charlotte S Jørgensen

Antibody testing, either using enzyme-linked immunosorbent assay (ELISA) or point-of-care (POC) lateral flow immunoassays, may overcome some of these challenges. SARS-CoV-2-specific antibodies can be detected in in serum of approximately 40% of COVID-19 patients as early as seven days after the onset of symptoms, with seroconversion rates rapidly increasing to >90% by day 14 [7] . In recent studies, antibody testing has been shown to be more sensitive than viral nucleic acid detection after approximately eight days of COVID-protein subunit 1 (S1) are detected in human serum or plasma. Briefly, 1:101 diluted serum samples were added to wells coated with recombinant SARS-CoV-2 antigen and incubated for 60 minutes at 37 °C. Wells were washed three times followed by the addition of HRP-conjugated anti-human IgA or IgG and subsequent incubation for 30 minutes at 37 °C. Wells were washed three times and a chromogen solution was added.