Impact of Respiratory Syncytial Virus (RSV) in adults 60 years and older in Spain.

Respiratory illnesses frequently lead to hospitalisation in adults aged 60 and older, especially due to respiratory virus infectious (RVIs). This study investigates hospitalisation patterns and characteristics of RVIs at HM Hospitals from October 2023 to March 2024. We retrospectively explored hospitalisations of patients aged 60 years and older with RVIs, gathering data on demographics, clinical profiles, comorbidities, and treatments. Outcomes included hospitalisation, ICU admissions, and mortality, independent factors associated with outcomes were identified using a multi-state model. From October 2023 to March 2024, from a total of 3,258 hospitalisation, 1,933 (59.3%) were identified as positive for RVIs. Overall, SARS-CoV-2 was the most prevalent (52.6%), followed by influenza (32.7%) and RSV (11.8%). Most RVIs involved single infections (88.2%). Hospitalisation rates increased with age for SARS-CoV-2, influenza, and RSV, with SARS-CoV-2 showing the highest rate, followed by influenza and RSV. In the multi-state model, RSV infection significantly increased ICU admission risk (HR: 2.1, 95%, p = 0.037). Age on admission (HR: 1.1, 95%, p < 0.001) and Charlson score (HR: 1.4, 95%, p = 0.001) were associated with transitioning from admission to death. ICU to death risks included age at admission (HR: 1.7, 95%, p < 0.001). RVIs in adults 60 years and older are associated with high hospitalisation and mortality rates, primarily driven by influenza and SARS-CoV-2, followed by RSV. Age and comorbidities significantly impact disease severity, emphasising the need for targeted prevention and management strategies for RSV in this vulnerable population.