Performance of Fujirebio Espline SARS-CoV-2 rapid antigen test for identifying potentially infectious individuals

Background. A possible approach to overcome the limitation of SARS-CoV-2 tests availability is the usage of rapid diagnostic tests. In this study, we focused on the potential effectiveness of a rapid SARS-CoV-2 antigen assay in specifically detecting patients with high nasopharyngeal viral load. Methods. Fujirebio Espline SARS-CoV-2 rapid antigen test was used for analyzing nasopharyngeal samples collected from a series of consecutive patients who were positive by molecular testing at the Pederzoli Hospital (Peschiera del Garda, Verona, Italy) between 5 and 19 April, 2021. Molecular testing was carried out with Altona Diagnostics RealStar® SARSCoV-2 RT-PCR Kit, detecting SASR-CoV-2 S and E genes. Results. The final study population consisted of 174 patients (mean age, 43±19 years; 80 women, 46%). A total number of 47/174 samples tested positive with Fujirebio Espline SARS-CoV-2, equating to 27% positive percent agreement (95% CI, 21-34%). The area under the curve of Fujirebio Espline SARS-CoV-2 for identifying samples with higher risk of infectivity was 0.89 (95% CI, 0.83 to 0.94; p<0.001), with 0.92 accuracy (95% CI, 0.87 to 0.96), 0.78 sensitivity (95% CI, 0.65 to 0.88) and 0.99 specificity (95% CI, 0.95 to 1.00). The mean cycle threshold value of the 13 false negative samples was 27.6 (range, 24.6-29.2) for S gene and 28.3 (range, 25.9-29.4) for E gene, respectively. Conclusion. Fujirebio Espline SARS-CoV-2 rapid antigen test displays excellent specificity for identifying potentially infectious patients, though subjects testing negative may still retain low infective potential.