Table 1.
Sensitivity (%) of the COVID-VIRO LFIA assay (AAZ) in detecting N antigen from nasopharyngeal and respective serum samples, classified by subgroups of NP viral load: high (Ct < 25), medium (25 ≤ Ct < 33), and low (33 ≤ Ct). Sensitivity of the COV-QUANTO assay is also shown. CI 95% are indicated in brackets. Ct values correspond to those of either the PCR Roche 6800 and/or Abbott Alinitym.
| High Viral Load (Ct < 25) | Medium Viral Load (25 ≤ Ct < 33) | Low Viral Load (33 ≤ Ct) | Global Results 11 ≤ Ct ≤ 41, (MED Ct 26.8) |
Results Considering Contagious Threshold (Ct ≤ 33) a |
|
|---|---|---|---|---|---|
| LFIA on nasopharyngeal samples | 99% n =73 (91.7–99.9) |
75% n = 85 (64.5–83.7) |
8% n = 25 (1.39−27.5) |
75% n = 183 (68.4–81.3) |
86% n = 160 (79−90.5) |
| LFIA on serum samples | 67% n = 18 (41.1−85.6) |
85% n = 20 (61.1−96) |
22% n = 18 (7.37−48.1) |
59% n = 56 (45−71.6) |
76% n = 38 (59.4−88) |
| ELISA N-Ag detection in Serum samples | 83% n = 18 (57.7–95.6) |
90% n = 20 (66.9–98.2) |
22% n = 18 (7.4–48.1) |
66% n = 56 (52−77.8) |
87% n = 38 (71.1–95.1) |
a Commonly accepted threshold for infectiousness of COVID-19 patient [21].