Table 3.
Performance Characteristics of Assays With RT-PCR, All Time Points and Average
| Group | Euro | Euro | Euro | GenScript | Wantai | Wantai |
|---|---|---|---|---|---|---|
| S1 IgA | S1 IgG | NCP IgG | sVNT | IgM | Total Ab | |
| (20% c/o)a | ||||||
| (20% c/o/equ)b | ||||||
| (25% c/o)c | ||||||
| Sensitivity [95% CI], % | Panel A | Panel B | ||||
| Infected-RT-PCR pos | ||||||
| Averaged | 58.0 [44.4–71.1] | 46.7 [35.4–59.6] | 51.4 [39.4–64.2] | 54.4 [42.3–66.7]a,b,c | 61.6 [41.8–80.8] | 71.6 [52.8–87.2] |
| <7 d | 29.3 [16.1–45.5] | 14.6 [5.6–29.2] | 20.0 [9.1–35.6] | 17.1 [7.2–32.1]a,b,c | 30.8 [9.1–61.4] | 38.5 [13.9–68.4] |
| 7–14 d | 55.9 [37.9–72.8] | 35.3 [19.7–53.5] | 41.2 [24.6–59.3] | 52.9 [35.1–70.2]a,b,c | 70.6 [44–89.7] | 76.5 [50.1–93.2] |
| >14 d | 88.9 [79.3–95.1] | 90.3 [81.0–96.0] | 93.1 [84.5–97.7] | 93.1 [84.5–97.7]a,b,c | 83.3 [72.1–91.4] | 100 [94.6–100] |
| Specificity [95% CI], % | ||||||
| Population | 95 [90.7–97.7] | 97.2 [93.6–99.1] | 99 [96.3–99.9] | 97.1 [94.6–98.7]a | 99.0 [94.6–100] | 99.5 [97.4–100] |
| 99.4 [97.7–99.9]b | ||||||
| 100 [98.8–100]c | ||||||
| Cross-reactive assessment | 86.7 [69.3–96.2] | 90.0 [73.5–97.9] | 83.3 [65.3–94.4] | 96.7 [82.8–99.9]a,b,c | 96.7 [82.8–99.9] | 97.2 [85.5–99.9] |
| PPV % (best–worst) 0.5% prevalence >14 d | 8.2 [4.1–17.0] | 14.0 [6.0–34.6] | 30.9 [10.2–79.4] | 13.8 [7.1–26.8]a | 29.5 [6.2–94.8] | 51.2 [15.3–97.6] |
| 42.2 [15.6–86.3]b | ||||||
| 100 [25.7–100]c | ||||||
| NPV % (best–worst) 0.5% prevalence >14 d | 99.9 [99.8–100] | 99.9 [99.9–100] | 100 [99.9–100] | 100 [99.9–100]a,b,c | 99.9 [99.9–100] | 100 [100–100] |
| PPV (best–worst) 10% prevalence >14 d | 66.3 [48.6–82.0] | 78.2 [58.4–92.1] | 90.8 [71.6–98.8] | 77.9 [63.0–89.0]a | 90.3 [59.5–99.8] | 95.9 [79.9–99.1] |
| 94.2 [80.4–99.3]b | ||||||
| 100 [88.4–100]c | ||||||
| NPV (best–worst) 10% prevalence >14 d | 98.7 [97.5–99.4] | 98.9 [97.8–99.6] | 99.2 [98.2–99.7] | 97.8 [94.1–99.7]a,b,c | 98.2 [96.8–99.1] | 100 [99.4–100] |
For all calculations, equivocal results were treated as positive. Best–worst: best- and worst-case intervals—intervals obtained by setting the corresponding sensitivity and specificity estimates to their upper/lower interval bound); Averaged, average sensitivity across the symptom onset categories.
Abbreviations: Ab, antibody; c/o, cutoff; Euro, Euroimmun; Ig, immunoglobulin; NCP, nucleocapsid; NPV, negative predictive value; PPV, positive predictive value; sVNT, surrogate virus neutralization test.
a20% c/o; sVNT ≥20% cutoff, no repeats.
b20% c/o/equiv; sVNT ≥20% cutoff + repeats for equivocals (18%–22%).
c25% c/o; ≥25% cutoff, no repeats.