Comparison of the Clinical Performances of the Abbott Alinity IgG, Abbott Architect IgM, and Roche Elecsys Total SARS-CoV-2 Antibody Assays

Critical evaluation of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) serologic assays is needed to guide clinical decision-making and ensure that these assays provide optimal benefit to patients and the public. Here, three commercially available assays with widespread distribution capabilities are compared. A total of 667 specimens, 103 from patients with confirmed SARS-CoV-2 infections and 564 collected prior to the emergence of SARS-CoV-2, were analyzed in parallel using the Roche Elecsys SARS-CoV-2 total antibody and Abbott Alinity SARS-CoV-2 IgG assays; a subset of 55 samples from patients with confirmed SARS-CoV-2 infections was additionally evaluated using the Abbott Architect SARS-CoV-2 IgM assay. Qualitative agreement between the Abbott IgG and Roche total antibody assays was 98.7% (658/667), with Cohen's kappa value of 0.919 (95% confidence interval [CI], 0.867 to 0.972). Qualitative agreements with the Abbott IgM assay were 92.7% (51/55, Abbott IgG) and 85.5% (47/55, Roche total antibody). Diagnostic specificities determined using pre-COVID-19 samples for the Abbott IgG and Roche total antibody assays were 99.65% (95% CI, 98.72 to 99.90%) and 100.00% (95% CI, 99.32 to 100.00%), respectively, spanning claims made by each manufacturer. Diagnostic sensitivities increased for all three assays with increasing time since the onset of symptoms. Among 51 patients with confirmed SARS-CoV-2 infections, 23 (45.1%), 24 (47.1%), and 22 (43.1%) were reactive by the Abbott IgG, Roche total antibody, and Abbott IgM assays, respectively, with sampling times 0 to 56 days post-positive PCR (median/mean, 2/6.2 days). Combining IgG and IgM screening identified 4/55 additional samples with detectable antibodies that would not have been observed using the assays independently. Notably, one immunocompromised patient with confirmed SARS-CoV-2 infection showed no detectable antibodies using any of the three assays 43 days after onset of symptoms.