Clinical features and outcomes of viral respiratory infections in adults during the 2023–2024 winter season

The role and impact of viral infections remain a subject of interest, yet comparative data on influenza A/B, RSV, and SARS-CoV-2 in both hospitalized and non-hospitalized patients are limited. In this observational study, we analyzed data from adult patients with respiratory infections who underwent rapid testing for Influenza A/B, RSV, SARS-CoV-2, and Adenovirus between October 2023 and March 2024. Symptoms at emergency department presentation, laboratory results, risk factors, clinical course, and outcomes were assessed. Among 1,402 patients with respiratory infections, Influenza A was the most prevalent virus and the leading cause of hospitalizations, with the longest stay (mean: 9.86 days). SARS-CoV-2 was the second most common, primarily affecting older patients (mean age: 79 years), associated with the highest in-hospital mortality. RSV ranked third in prevalence, had the highest hospitalization rate among those infected, and was characterized by bronchospasm, with 25% of hospitalized patients requiring high-flow nasal cannula (HFNC). Influenza B primarily affected younger individuals and had a negligible hospitalization rate. SARS-CoV-2 patients sought care the fastest, while RSV patients had the most prolonged symptom duration before seeking medical attention. Despite differences in care-seeking timing, most Flu-A, Flu-B, and SARS-CoV-2 patients recovered within 2-5 days, with no significant difference observed. Vaccine effectiveness against Influenza A was 49.5%. This estimate should be interpreted with caution due to potential confounding by age and comorbidities. These findings offer comparative insights into the clinical burden of respiratory viruses during the 2023-2024 season, reflecting patterns in the post-pandemic era.