Comparisons of Respiratory Syncytial Virus (RSV) and Influenza: Population Characteristics and Clinical Outcomes in Hospitalized Adults

BackgroundRespiratory syncytial virus (RSV) is under-recognized in hospitalized adults. We evaluated severity of acute respiratory illness (ARI) including intensive care unit (ICU) admission and mechanical ventilation in a national surveillance network. MethodsHospitalized adults who met a standardized ARI case definition were prospectively enrolled across three respiratory seasons from hospitals participating across all sites of the U.S. Hospitalized Adult Influenza Vaccine Effectiveness Network (HAIVEN, 2016-2019). Multivariable logistic regression was used to test associations between lab-confirmed infection and characteristics and clinical outcomes. ResultsAmong 10,311 hospitalized adults, 6% tested positive for RSV (n=622), 18.8% positive for influenza (n=1,940), and 75.1% negative for RSV and influenza (n=7,749). The proportion of adults with Congestive Heart Failure (CHF) or Chronic Obstructive Pulmonary Disease (COPD) was higher among adults with RSV than influenza (CHF: 37.3% vs. 28.8%, p<0.0001; COPD: 47.6% vs. 35.8%, p<0.0001). Patients with RSV had higher odds of experiencing length of stay [&ge;]8 days [OR=1.38 (95% CI: 1.06-1.80), p-value=0.02] and invasive or noninvasive mechanical ventilation [OR=1.45 (95% CI: 1.09-1.93), p-value=0.01] compared with influenza patients. ConclusionsOur findings suggest patients with RSV might incur worse outcomes than influenza in hospitalized adults, who are likely to have pre-existing cardiopulmonary conditions.