Table 1.
Antigen test performance according to the RT-PCR positivity or negativity used to determine the positive or negative COVID-19 status a.
| Antigen Test by COVID-19 Status (Positive or Negative) | ||||
|---|---|---|---|---|
| COVID-19 Area | Non-COVID-19 Area | |||
| Parameter | Positive | Negative | Positive | Negative |
| Positive results b | 119 | 15 | 18 | 48 |
| Negative results c | 56 | 893 | 25 | 1724 |
| Sensitivity, % (95% CI) | 68.0 (60.5–74.8) | … | 41.9 (27.0–57.9) | … |
| Specificity, % (95% CI) | 98.3 (97.3–99.1) | … | 97.3 (96.4–98.0) | … |
| Predictive value, % (95% CI) | ||||
| Positive | 88.8 (82.2–93.6) | … | 27.3 (17.0–39.6) | … |
| Negative | 94.1 (92.4–95.5) | … | 98.6 (97.9–99.1) | … |
Abbreviations: CI, confidence interval; COVID-19, coronavirus disease 2019; and RT-PCR, reverse-transcription polymerase chain reaction. a The SD Biosensor STANDARD F COVID-19 Ag FIA test was used to detect SARS-CoV-2 antigen in the nasopharyngeal swab samples of patients who accessed COVID-19 or non-COVID-19 areas of the emergency department (see text for details). The positive or negative COVID-19 status was determined by the RT-PCR assay performed on a nasopharyngeal swab that was subsequently sampled from the patient according to clinical discretion (see text for details). b Data represent true- and false-positive results, as assessed in comparison with those obtained by the RT-PCR assay, respectively. c Data represent false- and true-negative results, as assessed in comparison with those obtained by the RT-PCR assay, respectively.