5. Specificity for non‐COVID cases by reference standard (IgG, IgM, total Ab).
|
Test groups (true negatives/non‐COVID cases) Specificity (95% CI) |
||||||
| Target | Pre‐pandemic | Suspected of COVID‐19 (PCR‐negative) |
Current healthy/ other disease (RT‐PCR‐negative) |
Current untested | Other/ mixed unclear | Comparison between groupsa |
| IgG | 179 (37,385/38,090) | 19 (1496/1569) | 29 (7239/7336) | 16 (2514/2561) | 28 (7319/7384) | |
|
98.9 (98.6, 99.1) |
97.8 (96.5, 98.6) |
98.5 (97.9, 98.9) |
98.6 (97.8, 99.1) |
98.4 (97.4, 99.1) |
P = 0.006 | |
| IgM | 83 (14,691/15,126) | 9 (532/597) | 20 (2652/2735) | 10 (2145/2195) | 19 (7088/7153) | |
|
98.6 (98.0, 99.1) |
96.0 (92.9, 97.8) |
97.9 (96.7, 98.6) |
98.1 (96.6, 98.9) |
98.3 (96.9, 99.1) |
P < 0.001 | |
| IgG/IgM | 68 (8989/9262) | 18 (1796/1887) | 7 (348/359) | 6 (705/713) | 20 (1809/1887) | |
|
99.2 (98.5, 99.5) |
98.2 (96.3, 99.1) |
97.9 (94.4, 99.2) |
98.4 (94.8, 99.5) |
97.2 (95.2, 98.4) |
P = 0.012 | |
|
Total antibodies (Ab) |
45 (12,166/12,207) | 4 (534/540) | 4 (364/364) | 3 (1329/1329) | 3 (5373/5388) | |
|
99.8 (99.6, 99.9) |
99.5 (97.9, 99.9) |
100a (99.0, 100)** |
100a (99.7, 100)** |
99.4 (97.2, 99.9) |
P = 0.056 | |
Ab: antibody CI: confidence interval PCR: polymerase chain reaction RT‐PCR: reverse transcription polymerase chain reaction
aP values were generated using the likelihood ratio test by comparing the model including a covariate for each reference standard group to the model without the covariate; the "Other/mixed/unclear" group was not included in the comparison.
bEstimates and confidence intervals by summing the counts of true positive and false negative across 2 x 2 tables
c97.5% one‐sided exact binomial confidence interval