Table 1.
Specificity and Sensitivity of Single Antigen or Combination Antigen in Detecting SARS-CoV-2 IgG in Convalescent Saliva 1–9 Months After Symptom Onset and Prepandemic Saliva
| Antigen | Convalescent (n = 74) | Prepandemic (n = 23)a | ||||
|---|---|---|---|---|---|---|
| Sensitivity, % | No. Positive | No. Negative | Specificity, % | No. Positive | No. Negative | |
| Single antigen | ||||||
| Spike-f | 88 | 65 | 9 | 100 | 0b | 23 |
| S1 | 62 | 46 | 28 | 100 | 0 | 23 |
| NC-C | 66 | 49 | 25 | 100 | 0 | 23 |
| Combination antigen | ||||||
| Spike-f + S1 | 62 | 46 | 28 | 100 | 0 | 23 |
| Spike-f + NC-C | 66 | 49 | 25 | 100 | 0 | 23 |
| S1 + NC-C | 57 | 42 | 32 | 100 | 0 | 23 |
| Spike-f + S1 + NC-C | 72 | 53 | 21 | 100 | 0 | 23 |
Abbreviations: NC-C, nucleocapsid c-terminal chain; S1, spike S1 domain; spike-f, spike glycoprotein.
aAn additional 12 independent prepandemic saliva samples were used to establish assay cutoffs.
bOne sample shows intensity signal at cutoff level.