Table 3.
Comparison of Results From Self-LFIA and ALFA, ECLIA, and SARS-CoV-2 Neutralization Titer (NT)
| Self- LFIA | NT Positive (Median (IQR) Titer) |
NT Negative (Median (IQR) Titer) |
Total (Median (IQR) Titer) |
Performance (95% CI) |
|---|---|---|---|---|
| Positive | 133 (20.0; 10.0–113.1) | 34 (0.1; 0.1–0.1) | 167 (14.1; 7.1–80.0) | Sensitivity: 78.7 (71.8–84.6) |
| Negative | 36 (10.0;7.1–14.1) | 47 (0.1; 0.1–0.1) | 83 (0.1; 0.1–10.0) | Specificity: 58.0 (46.5–68.9) |
| Total | 169 (20.0;10.0–80.0) | 81 (0.1; 0.1–0.1) | 250 (10.0; 0.1–28.3) | … |
| ALFA | ||||
| ȃPositive | 142 (20.0; 10.0–104.8) | 41 (0.1; 0.1–0.1) | 183 (14.1; 7.1–56.6) | Sensitivity: 91.6 (86.1–95.5) |
| ȃNegative | 13 (10.0;7 .1–14.1) | 34 (0.1; 0.1–0.1) | 47 (0.1; 0.1–7.1) | Specificity: 45.3 (33.8–57.3) |
| ȃTotal | 155 (20.0; 10.0–80.0) | 75 (0.1; 0.1–0.1) | 230 (10.0; 0.1–28.3) | … |
| ECLIA (≥0.8 U mL–1) | ||||
| ȃPositive | 169 (20; 10–80) | 81 (0.1; 0.1–0.1) | 250 (10; 0.1–28.3) | Sensitivity: 100% (97.8–100) |
| ȃNegative | 0 … | 0 … | 0 … | Specificity: 0% (0–4.5) |
| Total | 169 (20; 10–80) | 81 (0.1; 0.1–0.1) | 250 (10; 0.1–28.3) | … |
Neutralization titers of 7.1 have been assigned an arbitrary threshold of 0.1, N = 250 (Self-LFIA) and N = 230 (ALFA).
Abbreviations: ALFA, automated image analysis; CI, confidence interval; ECLIA, electrochemiluminescence immunoassay; IQR, interquartile range; LFIA, lateral flow immunoassay; SARS-CoV-2, severe acute respiratory syndrome coronavirus 2.