Comparison of RSV, influenza and COVID-19 clinical characteristics in hospitalized adults in Valladolid–Spain, 2010–2022

<bold>Introduction:</bold> We aimed to describe the clinical characteristics of all laboratory-confirmed Respiratory Syncytial Virus (RSV) cases among adults aged ≥60 years in Valladolid during Jan2010–Aug2022 and to compare them with influenza and COVID-19 controls <bold>Methods:</bold> Retrospective cohort. We identified risk factors for hospitalization and for severity (length of hospital stay≥11 days, intensive care unit [UCI] admission, hospital readmission≤30 days and death). Using a multivariate logistic regression model, we compared severity between hospitalized cases and controls <bold>Results:</bold> We analyzed 706 RSV cases, 71 not hospitalized. Characteristics of hospitalized 635 RSV cases and 598 influenza and 60 COVID-19 controls were described. Risk factors for RSV hospitalization were resident in institutions (OR 3.33 [95%CI 1.32,8.44]), chronic lung (1.91 [1.13,3.23]), cardiovascular (5.23 [3.15,8.69]), kidney (2.42 [1.02,5.72]) or neurologic (2.35 [1.21, 4.56]) disease and coinfection (4.47 [2.11,9.50]). Risk factors for severity were institutionalized (1.55 [1.05,2.30]), hematologic disorder (1.99 [1.11,3.59]) and coinfection (2.03 [1.46,2.83]). RSV did not show statistically significant differences in any severity outcome vs influenza, while it had lower lenght of stay and ICU admission vs COVID-19 (adjusted OR 0.24 [0.13,0.46] and 0.18 [0.09,0.35]) <bold>Conclusions:</bold> RSV hospitalization outcomes are generally comparable to those from influenza and, except for lenght of stay and ICU admission, to COVID-19 in older adults. Currently both influenza and COVID-19 vaccines are part of the Spanish immunization program, RSV vaccination could also have a high clinical impact in this population