Table 1. Sensitivity of the SARS-CoV-2 in-house anti-RBD assay and Abbott anti-NP assay and correlation of results across the entire cohort, London, United Kingdom, 17 April–17 July 2020 (n = 906).
| Anti-RBD-positive | Anti-RBD-negative | Sensitivity % (95% CI) |
Concordance % (95% CI) |
Days since symptom onset Median (IQR) |
Binding ratio Median (IQR) |
||
|---|---|---|---|---|---|---|---|
| PCR-positive cases (n = 130) |
Anti-NP positive | 123 | 0 | Anti-RBD: 99.2 (95.8–100.0) Anti-NP: 94.6 (89.2–97.8) |
95.4 (90.2–98.3) |
36 (54) | Anti-RBD: 15.3 (12.7) Anti-NP: 6.42 (4.45) |
| Anti-NP-negative | 6 | 1 | |||||
| Symptomatic cases (n = 521) |
Anti-NP positive | 421 | 14 | NA | 88.5 (85.4–91.1) |
46.5 (50)a | Anti-RBD 9.55 (14.2) Anti-NP: 3.98 (4.67) |
| Anti-NP-negative | 46 | 40 | |||||
| Asymptomatic cases (n = 385) |
Anti-NP positive | 130 | 16 | NA | 86.2 (82.4–89.5) |
NA | Anti-RBD: 0.46 (5.27) Anti-NP: 0.39 (2.16) |
| Anti-NP-negative | 37 | 202 | |||||
anti-NP: anti-nucleocapsid antibody; anti-RBD: anti-receptor binding domain antibody; BR: binding ratio; CI: confidence interval; IQR: interquartile range; NA: not applicable; SARS-CoV-2: severe acute respiratory syndrome coronavirus-2.
a For time since symptom onset for symptomatic cases, data represent those with clearly defined date of onset (n = 376).
Calculated sensitivities of both the in-house anti-RBD and the Abbott anti-NP assay with comparison against SARS-CoV-2 PCR-positive cases. Agreement between assay results (positive and negative) are presented with a breakdown for both symptomatic and asymptomatic cases.