We comparatively assessed sensitivities and specificities of four commercial ELISAs and two rapid tests in 77 patients with PCR confirmed SARS-CoV-2 infection, grouped by intervals since symptom onset. While test sensitivities were low (<40%) within the first 5 days post disease onset, IgM-, IgA- and total antibody-ELISAs increased in sensitivity to >80% between the 6th and 10th day post symptom onset. The evaluated tests (including IgG and rapid tests) provided positive results in all patients at or after the 11th day post onset of disease. Specificities of the ELISAs were 83% (IgA), 98% (IgG) and 97% (IgM and total antibodies).
Keywords: SARS; antibodies; coronavirus; immunoassay.
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