TABLE 3.
Concordance between manufacturer enzyme immunoassay cutoff values for SARS-CoV-2 seropositivity and high nAb titers at various thresholds (n = 140)a
| Serologic assay | Positive percent agreement, no. (%) |
Negative percent agreement, no. (%) |
||||||
|---|---|---|---|---|---|---|---|---|
| nAb ≥20 (n = 92) |
nAb ≥40 (n = 80) |
nAb ≥80 (n = 64) |
nAb ≥160 (n = 35) |
nAb <20 (n = 48) |
nAb <40 (n = 60) |
nAb <80 (n = 76) |
nAb <160 (n = 105) |
|
| Euroimmun | 90 (97.8) | 80 (100) | 64 (100) | 35 (100) | 16 (33.3) | 18 (30.0) | 18 (23.7) | 18 (17.1) |
| EDI | 86 (93.5) | 74 (92.5) | 61 (95.3) | 34 (97.1) | 25 (52.1) | 25 (41.7) | 28 (36.8) | 30 (28.6) |
| ImmunoDiagnostics | 86 (93.5) | 76 (95.0) | 61 (95.3) | 35 (100) | 27 (56.3) | 29 (48.3) | 30 (39.5) | 33 (31.4) |
| Abbott | 90 (97.8) | 79 (98.8) | 64 (100) | 35 (100) | 9 (18.8) | 10 (16.7) | 11 (14.5) | 11 (10.5) |
| Roche | 90 (98.4) | 78 (97.5) | 63 (98.4) | 34 (97.4) | 6 (12.5) | 6 (10.0) | 7 (9.2) | 7 (6.7) |
a
Four thresholds for a high neutralizing antibody (nAb) AUC value were examined as the reference positive test. Borderline/indeterminate specimens were considered negative for the EIAs per manufacturers’ cutoff values.