9. Specificity by antigen type (IgG, IgM, total Ab).
|
Test groups (true negatives/non‐COVID cases) Specificity (95% CI) |
||||||
| Target |
Antigen subgroup |
Pre‐pandemic | Suspected of COVID‐19 |
Current RT‐PCR negative |
Current untested | Other/mixed unclear |
| IgG | N‐based | 55 (13,929/14,159) | 7 (542/559) | 6 (834/840) | 4 (697/705) | 6 (508/526) |
|
99.1 (98.7, 99.4) |
97.3 (94.5, 98.7) |
99.4 (97.9, 99.8) |
99.0 (97.6, 99.6) |
97.6 (93.4, 99.2) |
||
| S‐based | 66 (14,331/14,615) | 7 (696/722) | 11 (4569/4604) | 7 (521/525) | 12 (836/854) | |
|
98.9 (98.4, 99.2) |
96.9 (94.0, 98.4) |
98.4 (96.6, 99.2) |
99.3 (98.0, 99.8) |
98.4 (96.4, 99.3) |
||
| N‐ and S‐based | 37 (7325/7449) | 3 (197/204) | 9 (1661/1706) | 5 (1296/1331) | 5 (5550/5573) | |
|
99.0 (98.4, 99.4) |
95.8 (87.7, 98.7) |
98.0 (95.7, 99.1) |
97.9 (95.9, 98.9) |
98.7 (96.0, 99.6) |
||
| Unclear/not reported | 21 (1800/1867) | 2 (61/84) | 3 (175/186) | ‐ | 5 (425/431) | |
|
98.8 (97.0, 99.5) |
73.4 (53.3, 87.0) |
96.5 (83.9, 99.3) |
‐ |
98.8 (96.2, 99.6) |
||
| Comparison between groupsa | P = 0.594 | P = 0.804 | P = 0.276 | P = 0.167 | P = 0.748 | |
| IgM | N‐based | 22 (5564/5674) | 3 (258/268) | 2 (99/99) | 3 (455/464) | 5 (476/501) |
|
98.4 (96.9, 99.2) |
96.3 (93.2, 98.0) |
100b (96.3, 100)** |
98.6 (95.0, 99.6) |
95.9 (89.9, 98.4) |
||
| S‐based | 16 (2800/2870) | 1 (38/40) | 6 (720/746) | 2 (400/400) | 4 (379/387) | |
|
98.3 (96.3, 99.2) |
95.0 (82.1, 98.7) |
96.9 (93.2, 98.6) |
100b (99.1, 100)c |
98.4 (94.6, 99.5) |
||
| N‐ and S‐based | 28 (4957/5114) | 3 (194/204) | 9 (1655/1704) | 5 (1290/1331) | 5 (5809/5834) | |
|
98.9 (97.8, 99.5) |
95.1 (91.1, 97.3) |
97.8 (95.5, 99.0) |
98.4 (95.5, 99.4) |
99.0 (97.2, 99.6) |
||
| Unclear/not reported | 17 (1370/1468) | 2 (42/85) | 3 (178/186) | ‐ | 5 (424/431) | |
|
97.2 (93.9, 98.8) |
47.3 (9.9, 88.0) |
95.7 (91.6, 97.8) |
‐ |
98.6 (95.7, 99.6) |
||
| Comparison between groupsa | P = 0.653 | P = 0.803 | P = 0.089 | P = 0.04 | P = 0.173 | |
| IgG or IgM | N‐based | 11 (2595/2637) | 3 (236/236) | 1 (4/4) | 4 (361/368) | 5 (416/451) |
|
99.2 (96.7, 99.8) |
100b (98.4, 100)c |
100b (39.8, 100)c |
98.1 (96.1, 99.1) |
94.1 (87.9, 97.2) |
||
| S‐based | 16 (3748/3800) | 7 (994/1018) | 3 (231/238) | 2 (344/345) | 5 (468/479) | |
|
99.4 (97.9, 99.8) |
99.0 (95.3, 99.8) |
97.1 (94.0, 98.6) |
99.7 (97.9, 100) |
98.0 (95.2, 99.2) |
||
| N‐ and S‐based | 19 (1106/1170) | 4 (385/406) | 1 (38/39) | ‐ | 4 (491/513) | |
|
98.8 (96.1, 99.6) |
95.6 (82.8, 99.0) |
97.4 (83.9, 99.6) |
‐ |
96.3 (91.5, 98.5) |
||
| Unclear/not reported | 21 (1347/1455) | 4 (181/227) | 2 (75/78) | ‐ | 6 (434/444) | |
|
97.6 (94.4, 99.0) |
79.7a (73.9, 84.8)d |
96.2 (88.7, 98.8) |
‐ |
98.3 (94.6, 99.5) |
||
| Comparison between groupsa | P = 1 | P = 0.021 | P = 0.617 | ‐ | P = 0.236 | |
| Total Ab | N‐based | 26 (5808/5824) | 3 (303/306) | 2 (277/277) | 2 (1029/1029) | 1 (26/26) |
|
99.9 (99.6, 99.9) |
99.0 (97.0, 99.7) |
100b (98.7, 100)c |
100b (99.6, 100)c |
100b (86.8, 100)c |
||
| S‐based | 19 (6358/6383) | 1 (231/234) | 2 (87/87) | 1 (300/300) | 1 (97/100) | |
|
99.8 (99.4, 99.9) |
98.7 (96.1, 99.6) |
100b (95.8, 100)c |
100a (98.8, 100)c |
97.0 (91.1, 99.0) |
||
| N‐ and S‐based | ‐ | ‐ | ‐ | ‐ | 1 (5250/5262) | |
| ‐ | ‐ | ‐ | ‐ |
99.8 (99.6, 99.9) |
||
| Unclear/not reported | ‐ | ‐ | ‐ | ‐ | ‐ | |
| ‐ | ‐ | ‐ | ‐ | ‐ | ||
| Comparison between groupsa | P = 0.525 | P = 0.741 | ‐ | ‐ | ‐ | |
CI: confidence interval N: nucleocapsid protein RT‐PCR: reverse transcription polymerase chain reaction S: spike‐protein
aP values were generated using the likelihood ratio test comparing the model including a covariate for test method to the model without the covariate for each reference standard group per target antibody; for each comparison, the 'unclear/not reported' group was not included
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
d95% exact binomial confidence interval