Respiratory Syncytial Virus Versus Influenza in Hospitalized Adults During the Post-Pandemic Era: Clinical Characteristics, Similarities and Discrepancies

Respiratory syncytial virus (RSV) has emerged as a major cause of hospitalization among adults in the post-pandemic era. We studied the epidemiological findings and the outcomes of patients hospitalized with influenza or RSV during the first post-pandemic respiratory virus season in Northern Greece. This multicenter retrospective study included adults hospitalized with RSV or influenza between November 2023 and May 2024 at two hospitals in Thessaloniki, Greece. Epidemiological data, clinical, laboratory, and radiological findings, vaccination status, and clinical outcomes were retrieved and compared. Twenty-seven patients with RSV and forty-eight with influenza were included. RSV patients were older (77.7 vs. 67.2 years, p < 0.01) with a higher prevalence of cardiovascular disease, chronic pulmonary disease, and malignancy, and had tachypnea more frequently at presentation (p = 0.024). No significant differences in the laboratory, radiological findings, and outcomes between the two groups were recorded. No patient was vaccinated against RSV, while 20.8% of the influenza patients had been previously vaccinated. RSV patients had a greater burden of comorbidities, whereas overall clinical outcomes did not significantly differ from those with influenza.