Summary of performance of diagnostic tests for COVID-19 from the literature
| Test | Test performance |
|---|---|
| One URT swab | Sensitivity 66–71% (one outlier 90%)8–10 Specificity unknown – low level positives may be indistinguishable from environmental contamination, affecting specificity |
| Two URT swabs | Sensitivity 94–98%8–10 |
| Three URT swabs | Sensitivity 98–100%8,10 |
| CT | Sensitivity 71–100%4,5,9,13–15 – can be as low as 44% in early or asymptomatic disease16,17 Specificity 53%14 Both sensitivity and specificity are operator-dependent15 |
| One CXR | Sensitivity 64% based on a single publication, overall limited evidence and skewed by practice in China where CT is the norm10 |
Abbreviations: URT = upper respiratory tract; CT = computed tomography; CXR = chest radiograph