Table 4 Agreement between qualitative results provided by flow cytometry-based S immunoassay and two commercially-available SARS-CoV-2 CLIA targeting either the trimeric S protein or the receptor binding domain (RBD).
Assays under comparison | Percent agreement between qualitative results (95% CI) | Kappa index (P value) | |
|---|---|---|---|
Positive | Negative | ||
IgG FCI/Roche Elecsys® anti-SARS-CoV-2 S | 97.7 (95.4–99.9) | 84.4 (73.8–95.0) | 0.84 (< 0.001) |
IgA FCI/Roche Elecsys® anti-SARS-CoV-2 S | 96.0 (93.1–98.9) | 87.5 (77.2–97.7) | 0.82 (< 0.001) |
IgG + IgA FCI/Roche Elecsys® anti-SARS-CoV-2 S | 96.1 (92.2–98.9) | 92.1 (83.5–100) | 0.85 (< 0.001) |
IgG FCI/Liaison® SARS-CoV-2 TrimericS IgG assay | 88.2 (83.3–93.1) | 91.1 (82.8–99.4) | 0.69 (< 0.001) |
IgA FCI/Liaison® SARS-CoV-2 TrimericS IgG assay | 86.8 (81.8–91.8) | 95.0 (88.25–100) | 0.68 (< 0.001) |
IgG + IgA FCI/Liaison® SARS-CoV-2 TrimericS IgG assay | 86.4 (81.4–91.5) | 97.4 (92.3–100) | 0.68 (< 0.001) |
Roche Elecsys® Anti-SARS-CoV-2 S/Liaison® SARS-CoV-2 TrimericS IgG assay | 89.8 (85.3–94.4) | 97.6 (93.0–100) | 0.76 (< 0.001) |
