COVID-19, influenza, and respiratory syncytial virus are leading causes of severe acute respiratory infection (SARI). As viral dynamics shift post-pandemic, comparing their clinical profiles is essential for optimizing management and vaccination strategies. We conducted a retrospective observational study of adults hospitalized with PCR-confirmed COVID-19, influenza, or RSV over three consecutive seasons (2021–2024). We compared clinical features, comorbidities and outcomes, including mortality, intubation rates and respiratory deterioration. Multivariable analyses were performed where virus was the independent variable and respiratory deterioration, intubation rate and mortality, Charlson Comorbidity Index, smoking status and pneumonia were co-variates. 263 patients were analyzed. Key findings revealed distinct clinical profiles: influenza patients were significantly younger, while COVID-19 was the predominant cause of viral pneumonia. RSV patients presented with the most severe oxygenation deficit upon admission and experienced the highest rate of respiratory deterioration (28%). Logistic regression analyses demonstrated that pneumonia [OR 2.81, 95% Confidence Interval (CI): 1.23–6.43, p = 0.01] and RSV (OR 2.8, 95% CI: 1.16–6.63, p = 0.02) were independently associated with respiratory deterioration. Similarly, pneumonia (OR 4.86, 95%CI: 1.62–17.36, p < 0.01] and RSV (OR 4.67, 95%CI: 1.5–14.34, p < 0.01) were independently associated with high risk of intubation. Among patients hospitalized because of COVID-19, RSV and Influenza, pneumonia and RSV were linked with respiratory deterioration and increased risk of intubation but not with death.