Table 2.
Overview of positive percent agreement (PPA) of the Roche Elecsys Anti-SARS-CoV-2 Antigen assay with the Roche cobas SARS-CoV-2 IVD test in NPS and saliva.
| Cobas E-Gene Ct Value a | NPS (All) | NPS (Paired) | Saliva | |||
|---|---|---|---|---|---|---|
| N (cum. b) |
PPA, % (95% CI) |
N (cum.) |
PPA, % (95% CI) |
N (cum.) |
PPA, % (95% CI) |
|
| ≤26 | 134 | 100 97.3–100 |
57 | 100 93.7–100.0 |
22 | 100 84.6–100 |
| ≤27 | 138 | 100 97.4–100 |
60 | 100 94.0–100.0 |
26 | 96.2 80.4–99.9 |
| ≤28 | 150 | 100 97.6–100 |
65 | 100 94.5–100.0 |
34 | 91.2 76.3–98.1 |
| ≤29 | 156 | 99.4 96.5–100 |
70 | 98.6 92.3–100 |
37 | 86.5 71.2–95.5 |
| ≤30 | 160 | 98.8 95.6–99.8 |
73 | 97.3 90.4–99.7 |
42 | 78.6 63.2–89.7 |
| ≤31 | 162 | 98.8 95.6–99.9 |
75 | 97.3 90.7–99.7 |
50 | 66.0 51.2–78.8 |
| ≤32 | 165 | 97.0 93.1–99 |
75 | 97.3 90.7–99.7 |
60 | 55.0 41.6–67.9 |
| ≤33 | 170 | 94.7 90.2–97.6 |
75 | 97.3 90.7–99.7 |
65 | 50.8 38.1–63.4 |
| ≤34 | 172 | 93.6 88.8–96.8 |
76 | 96.1 88.9–99.2 |
72 | 47.2 35.3–59.3 |
| ≤35 | 177 | 91.5 86.4–95.2 |
79 | 93.7 85.8–97.9 |
73 | 46.6 34.8–58.6 |
| Overall (≤40) |
187 | 87.2 81.5–91.6 |
87 | 86.2 77.1–92.7 |
87 | 40.2 29.9–51.3 |
a sample type-specific Ct values; b cumulative.