Clinical course of hospitalizations with Influenza, SARS-CoV-2 and respiratory syncytial virus (RSV) infections in the season 2024/2025 in a large German primary care centre and comparison with the previous two years

Background Respiratory viruses including influenza, respiratory syncytial virus (RSV), and SARS-CoV-2 continue to cause morbidity and mortality, particularly in older adults and young children. We aimed to assess their clinical impact and outcomes in the 2024/25 season in comparison with the past two seasons, using data from the same primary care hospital in Southern Germany. Methods Retrospective analysis of patients hospitalized with PCR-confirmed SARS-CoV-2, Influenza A/B, or RSV infection between August 2024 and April 2025 in the internal, neurological and paediatric departments. Clinical characteristics including comorbidities, symptoms, laboratory parameters and outcomes were analyzed, with focus on the need/type of respiratory support, admission to intensive care, and death. Results Of 723 patients included, 714 had mono infections with SARS-CoV-2 (40.0%), influenza A (35.7%) or B (8.2%), or RSV (14.8%), with high frequency in young children and older adults. Among patients ≥ 18 years of age (n = 514, 48.3% SARS-CoV-2, 41.3% Influenza A, 3.1% Influenza B, 6.6% RSV), admission to the intensive care unit (ICU) was required in 42 patients (8.1% SARS-CoV-2, 8.5% Influenza A, 6.3% Influenza B, 8.8% RSV), and 51 patients died (13.3% of SARS-CoV-2, 6.1% Influenza A, 6.3% Influenza B, 11.8% RSV). The highest demand for oxygen therapy and mechanical invasive ventilation occurred with RSV. Among patients < 18 years of age (n = 209, 19.6% SARS-CoV-2, 22.0% Influenza A, 21.1% Influenza B, 34.9% RSV), 5 were admitted to the ICU (4.8% of SARS-CoV-2, 0.0% Influenza A, 4.5% Influenza B, 1.5% RSV), and none died. Compared to the two preceding seasons, there were variations but no statistically significant changes in prevalence and outcome. Mortality in adults tended to increase for SARS-CoV-2 and decrease for RSV. Moreover, Influenza A and RSV activity shifted toward later months, and Influenza B emerged prominently only in 2024/25. Conclusions During the 2024/25 season, the distribution of viral respiratory tract infections showed no major differences compared to the two previous seasons; however, Influenza B re-emerged in substantial numbers. Overall, infections with SARS-CoV-2 were still most frequent, and in adult patients mortality tended to be twice as high as in patients with influenza.