Table 3.

Assay specificities

Immunoassay	No. of negative controls1	No. testing negative	%	95% CI
Epitope IgG	230	228	99.1	97.9% – 100%
Epitope IgM	230	227	98.7	97.2% – 100%
Ragon/MGH IgG2	232	231	99.6	98.7% – 100%
Roche3	232	231	99.6	98.7% – 100%
Simoa (Early)4	232	230	99.1	97.9% – 100%

^1.Given limited negative control aliquots, the Epitope assays were tested against 230 samples, versus 232 for the remaining assays

^2.For specificity of Ragon/MGH IgM and IgA see supplementary materials.

^3.The Roche Elecsys Anti-SARS-CoV-2 immunoassay detects IgG and likely IgM and IgA; details of other isotypes are not provided by manufacturer

^4.Specificity of the Simoa multiplex assay Early Model. For specificities of the Late and 12-Parameter Models see supplementary materials.