Viral Pathogen-Specific Severe Acute Respiratory Infections in Hospitalised Adults in Europe: Epidemiological Findings from the id.DRIVE Study 2024–2025

INTRODUCTION: Lower respiratory tract infections represent a major public health burden, but adult data on respiratory viruses except influenza and COVID-19 are limited. Most European surveillance systems report aggregate data lacking patient-level detail. METHODS: We utilised the multicountry id.DRIVE surveillance study data to describe the epidemiology, clinical characteristics, and outcomes of adults hospitalised with pathogen-specific severe acute respiratory infections (SARI) during 2024-2025. Adults (≥ 18 years) hospitalised with SARI across 17 hospitals in Spain, Italy, and Germany between 1 September 2024 and 31 August 2025 were included. All participants were tested using reverse transcription polymerase chain reaction for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), respiratory syncytial virus (RSV), and influenza A/B (testing additional respiratory pathogens varied by hospital). Descriptive analyses were stratified by pathogen. RESULTS: Of 8730 included participants (median age, 77 years), 14.3% (n = 1249) tested positive for influenza A, 6.9% (n = 606) SARS-CoV-2, 6.4% (n = 554) RSV, and 0.8% (n = 74) for influenza B. Positivity peaked for influenza and RSV in December-January, and for SARS-CoV-2 in July. Comorbidity burden was substantial: 51.9% of all SARI participants had ≥ 3 chronic conditions, reaching 62.3% in those with RSV. RSV-positive SARI patients were older (median age, 80 years); oxygen therapy was required in 72.0%, non-invasive ventilation in 12.3%, and in-hospital mortality was 9.4%. Over 75.0% of SARI cases positive for a respiratory virus received antibiotics during hospitalisation. CONCLUSION: Viral pathogens remain a major cause of adult SARI hospitalisations in Europe. Our findings highlight the continued burden and seasonal diversity of viral respiratory pathogens, supporting the value of integrated, pathogen-specific SARI surveillance guiding prevention strategies.