Diagnostic Performance of a Combined Rapid Antigen Test for Detecting SARS-CoV-2, Influenza Virus, and Respiratory Syncytial Virus in Symptomatic Patients in Tertiary Care.

Rapid antigen diagnostic tests (RDTs) can rapidly detect respiratory pathogens, allowing for the prompt initiation of infection control measures and the prevention of nosocomial spread within hospital settings. In this study, we prospectively evaluated the diagnostic performance of a combined RDT from AllTest Biotech for the simultaneous detection of SARS-CoV-2, influenza virus (IV-A/B), and respiratory syncytial virus (RSV). We compared its diagnostic performance to the Xpert-Xpress-SARS-CoV-2/Flu/RSV molecular test using 100 naso-oropharyngeal swabs (Ct-values ≤ 35), collected from symptomatic patients with acute respiratory tract infections (RTIs) at our tertiary care hospital. The RDT showed a sensitivity of 60% (95%CI: 43.4%-74.7%) for SARS-CoV-2, with lower sensitivities for RSV at 60.0% (95%CI: 38.9%-78.2%) and IV-A/B at 54.3% (95%CI: 36.9%-70.8%). Higher sensitivities of 100% were achieved for all three viruses in respiratory samples with higher viral loads (Ct-values ≤ 25). The RDT demonstrated high specificity of > 99% for SARS-CoV-2, IV-A/B, and RSV. In conclusion, the Alltest-SARS-CoV-2/IV-A + B/RSV RDT is effective for detecting SARS-CoV-2, IV-A/B, and RSV in samples with high viral loads, but its sensitivity significantly declines at Ct-values above 25. Therefore, negative RDT results should be confirmed with nucleic acid testing in symptomatic patients with RTIs to prevent severe consequences for clinical management.