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

Background Respiratory 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. Methods Hospitalized 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. Results Among 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 ≥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. Conclusions Our findings suggest patients with RSV might incur worse outcomes than influenza in hospitalized adults, who are likely to have pre-existing cardiopulmonary conditions. ### Competing Interest Statement LL received grant support paid to her institution by Centers for Disease Control and funding from Janssen Scientific Affairs for being a Consultant Representative on an RSV analyses paid to institution. MJG received institutional grant support from the Centers for Disease Control (CDC) and funding from CDC and CDC-Abt Associates (influenza vaccine research), MedImmune (live attenuated influenza vaccine research), Janssen (RSV severity in infants research) and Pfizer (Meningococcal B vaccine in adolescent education). ETM received institutional grant support from CDC, CDC-Abt Associates for studies of influenza vaccine and Merck for studies of RSV epidemiology. ### Funding Statement This work was supported by the Centers for Disease Control and Prevention (cooperative agreement IP15-002; grant numbers U01IP000979 to the Tennessee site, U01IP000974 to the Michigan site, U01IP000972 to the Texas site, and U01IP000969 to the Pennsylvania site); and supported in part at the Pennsylvania site by the National Institutes of Health Clinical and Translational Science Award program (grant number UL1TR001857). The findings and conclusions in this report are those of the authors and do not necessarily represent the official position of the Centers for Disease Control and Prevention (CDC), the US Public Health Service, or funding agency. ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: To participate in the study, written informed consent was provided by patients or a proxy/surrogate. The University of Michigan Institutional Review Board, the Vanderbilt University Medical Center Institutional Review Board, the University of Pittsburgh Human Research Protection Office, and the Baylor Scott & White Research Institute Institutional Review Boards gave ethical approval for this work. The Centers for Disease Control and Prevention Institutional Review Board issued a reliance on the site specific approvals. I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines and uploaded the relevant EQUATOR Network research reporting checklist(s) and other pertinent material as supplementary files, if applicable. Yes All data produced in the present study may be requested from study authors and the Centers for Disease Control and Prevention.