Table 2.
Diagnostic performance of the index and serial combined nasal and throat swab for the primary outcome of a diagnosis of confirmed or probable COVID-19
| Serial tests | True negative | False negative | True positive | False positive | Sensitivity (95% CI) |
Negative predictive value (95% CI) |
Positive predictive value (95% CI) |
Specificity (95% CI) |
|---|---|---|---|---|---|---|---|---|
| 1 (index test) | 868 | 241 | 255 | 4 | 51.4 (48.8–54.1) | 78.3 (76.0–80.4) | 98.5 (97.7–99) | 99.5 (99.0–99.8) |
| 2 | 459 | 141 | 212 | 5 | 60.1 (56.7–63.4) | 76.5 (73.5–79.3) | 97.7 (96.4–98.5) | 98.9 (98.0–99.4) |
| 3 | 235 | 76 | 164 | 7 | 68.3 (64.0–72.3) | 75.6 (71.5–79.2) | 95.9 (93.7–97.3) | 97.1 (95.2–98.3) |
| 4 | 142 | 36 | 125 | 7 | 77.6 (72.7–81.9) | 79.8 (75.0–83.9) | 94.7 (91.6–96.7) | 95.3 (92.3–97.2) |
| 5 | 94 | 24 | 94 | 6 | 79.7 (73.8–84.5) | 79.7 (73.8–84.5) | 94.0 (90.0–96.5) | 94.0 (90.0–96.5) |
| 6 | 62 | 11 | 75 | 6 | 87.2 (81.0–91.6) | 84.9 (78.4–89.7) | 92.6 (87.3–95.8) | 91.2 (85.6–94.7) |
| 7 | 46 | 10 | 55 | 6 | 84.6 (77.0–90.0) | 82.1 (74.2–88.0) | 90.2 (83.4–94.3) | 88.5 (81.4–93.1) |
| 8 | 31 | 6 | 43 | 4 | 87.8 (79.1–93.2) | 83.8 (74.5–90.2) | 91.5 (83.6–95.8) | 88.6 (80.0–93.7) |