Advancing respiratory virus diagnostics: integrating the nasal IFN-I score for improved viral detection

This study aimed to demonstrate the utility of the nasal Type I interferon (IFN-I) response as a marker for respiratory viral infections (RVIs) and its potential to enhance diagnosis when combined with first-line PCR tests for Influenza A/B, RSV, and SARS-CoV-2. Nasopharyngeal swabs (NPS) from patients at Hospices Civils de Lyon (November 2022–April 2024) suspected of viral infections (n = 788) and from healthy controls (n = 53) were analysed. The IFN-I score was measured using the FILMARRAY® IFN-I pouch prototype, which detects four interferon-stimulated genes. The study evaluated the performance of the IFN-I score in detecting samples positive for viruses by first-line PCR and assessed its benefit in diagnosing RVIs in samples initially classified as negative by PCR. Out of 788 NPS included, 504 (64%) were positive with the first-line PCR tests, and IFN-I score was significantly higher in those samples (median [IQR]: 13.00 [2.76–45.40]) compared to ones collected from healthy controls (1.09 [0.67–1.30]; p