TABLE 3.
Performance of surrogate tests against a subset of 136 high‐titer sera (nAb titers ≥160) from convalescent donors
| Surrogate test | Sens % (CI95%) | Spec % (95% CI) | PPV % (95% CI) | NPV % (95% CI) | AUC (95% CI) | LR + (95% CI) | Youden |
|---|---|---|---|---|---|---|---|
| Gen Script ≥68% | 83.8 (76.5–89.6) | 87.3 (75.5–94.7) | 94.2 (88.4–97.6) | 68.6 (56.4–79.1) | 0.86 (0.80–0.91) | 6.59 (3.28–13.2) | 0.711 |
| Vitros Spike ≥9.5 | 99.3 (96–100) | 30.9 (19.1–44.8) | 78.0 (71.1–84) | 94.4 (72.7–99.9) | 0.65 (0.59–0.71) | 1.44 (1.2–1.72) | 0.302 |
| Roche Spike ≥132 UI/ml | 71.3 (62.9–78.7) | 90.9 (80–97) | 95.1 (88.9–98.4) | 56.2 (45.3–66.7) | 0.81 (0.76–0.87) | 7.85 (3.38–18.2) | 0.622 |
| Roche anti‐NP >109 | 45.6 (37–54.3) | 94.5 (84.9–98.9) | 95.4 (87.1–99) | 41.3 (32.6–50.4) | 0.70 (0.65–0.75) | 8.36 (2.74–25.5) | 0.401 |
| ICB IgG anti‐NP S/CO ≥5.0 | 86.0 (79–91.4) | 72.7 (59–83.9) | 88.6 (82–93.5) | 67.8 (54.4–79.4) | 0.80 (0.73–0.86) | 3.15 (2.04–4.88) | 0.588 |
| Comb OSp9 + RBD68 | 83.8 (76.5–89.6) | 87.3 (75.5–94.7) | 94.2 (88.4–97.6) | 68.6 (56.4–79.1) | 0.86 (0.80–0.91) | 6.59 (3.28–13.2) | 0.711 |
| Comb RSp132 + RBD68 | 25.0 (18.0–33.1) | 100 (93.5–100) | 100 (89.7–100) | 35.0 (27.6–43.0) | 0.62 (0.50–0.66) | NE a | 0.250 |
Note: All AUCs had p < .0001 when compared to the standard CPE‐VNT test.
a
NE, Not possible to be estimated, due to absence of reactive samples in one of the four categories: nAb neg/test neg; nAb neg/test pos; nAb pos/test neg or nAb pos/test pos.