7. Sensitivity by test method by week after onset (IgG, IgM, total Ab).
| Target | Test method | Week 1 | Week 2 | Week 3 |
|
Test groups (true positives/COVID cases) Sensitivity (95% CI) | ||||
| IgG | By test method | |||
| ELISA | 56 (487/1780) | 62 (1783/2991) | 54 (1227/1416) | |
|
21.8 (17.1, 27.4) |
63.7 (58.7, 68.4) |
89.6 (86.5, 92.1) |
||
| CLIA | 46 (480/1616) | 51 (1541/2382) | 43 (1125/1282) | |
|
28.0 (22.0, 34.9) |
66.1 (60.8, 71.0) |
87.4 (83.5, 90.5) |
||
| Lateral flow/CGIA/ FIA | 83 (881/2816) | 85 (2122/3171) | 90 (1901/2236) | |
|
28.1 (23.5, 33.3) |
67.6 (63.6, 71.5) |
87.1 (84.3, 89.4) |
||
| Comparison between groupsa | P = 0.178 | P = 0.461 | P = 0.38 | |
| IgM | By test method | |||
| ELISA | 21 (670/208) | 21 (802/1217) | 16 (367/461) | |
|
29.3 (21.6, 38.4) |
68.2 (57.1, 77.5) |
84.5 (73.5, 91.4) |
||
| CLIA | 19 (208/536) | 17 (590/889) | 14 (488/613) | |
|
35.0 (25.5, 45.7) |
64.2 (51.3, 75.4) |
78.7 (65.0, 88.1) |
||
| Lateral flow/CGIA/FIA | 82 (1020/2819) | 82 (1970/3099) | 87 (1548/2142) | |
|
32.6 (28.1, 37.4) |
63.4 (57.6, 68.9) |
76.9 (71.4, 81.7) |
||
| Comparison between groupsa | P = 0.69 | P = 0.74 | P = 0.422 | |
| IgG/IgM | By test method | |||
| ELISA | 8 (67/197) | 8 (376/514) | 8 (225/237) | |
|
33.8 (21.6, 48.6) |
72.9 (64.5, 79.9) |
95.9 (91.0, 98.2) |
||
| CLIA | 4 (78/173) | 4 (224/286) | 2 (173/178) | |
|
43.9 (25.0, 64.8) |
75.9 (64.1, 84.7) |
97.3 (89.6, 99.3) |
||
| Lateral flow/CGIA/FIA | 90 (1439/3470) | 83 (2275/3115) | 91 (2127/2454) | |
|
40.5 (36.2, 44.9) |
74.6 (71.9, 77.2) |
88.7 (86.3, 90.7) |
||
| Comparison between groupsa | P = 0.634 | P = 0.886 | P = 0.006 | |
| Total antibodies (Ab) | By test method | |||
| ELISA | 6 (158/292) | 8 (304/342) | 7 (209/219) | |
|
56.5 (37.4, 73.8) |
88.5 (80.1, 93.6) |
96.4 (91.4, 98.6) |
||
| CLIA | 19 (252/660) | 20 (474/648) | 25 (685/782) | |
|
34.6 (24.3, 46.6) |
76.0 (68.2, 82.4) |
88.4 (83.6, 92.0) |
||
| Lateral flow/CGIA/FIA | 7 (103/272) | ‐ | ‐ | |
|
39.2 (7.9, 82.9) |
‐ | ‐ | ||
| Comparison between groupsa | P = 0.181 | P = 0.029 | P = 0.013 | |
CI: confidence interval CGIA: colloidal gold immunoassay CLIA: chemiluminescent immunoassay ELISA: enzyme linked immunosorbent assay FIA: fluorescence immunoassay
aP values were generated using the likelihood ratio test comparing the model for each target antibody by week after onset including a covariate for test method to the model without the covariate; comparison does not include the ‘unclear/not reported’ test method category