746. Characteristics of Respiratory Syncytial Virus (RSV) Infection Among Hospitalized Adults, United States, 2014–2017

Background Respiratory syncytial virus (RSV) vaccines are in clinical development for older adults. We described RSV infections among adults requiring hospitalization and risk factors for severe outcomes using a population-based platform, the Influenza Hospitalization Surveillance Network (FluSurv-NET). Methods Surveillance occurred October 1–April 30 (2014–2017) at sites located in seven states (California, Georgia, Michigan, Minnesota, New York, Oregon, and Tennessee) covering an annual catchment population of up to 13 million adults ≥18 years. Laboratory-confirmed RSV cases were identified using hospital and state public health laboratories, hospital infection preventionists, and/or reportable condition databases. Medical charts were reviewed for demographic and clinical data. International Classification of Diseases (ICD) discharge codes were abstracted. Odds ratios (Oregon) and 95% confidence intervals (CIs) were determined to assess risk factors for ICU hospitalization and deaths. Results A total of 2,326 hospitalized RSV cases were identified. Over half were ≥65 years (62%, n = 1,438/2,326), female (59%, n = 1,362/2,326), white (70%, n = 1,301/1,855), and had ≥3 underlying medical conditions (52%, n = 1,204/2,326). 20% (n = 398/2,000) were hospitalized in the ICU (median length of stay, 3 days; interquartile range, 1–6 days), and 5% (n = 96/2,001) died in the hospital. Congestive heart failure (CHF; OR: 1.4, 95% CI: 1.1–1.8) and chronic obstructive pulmonary disease (COPD; OR: 1.3, 95% CI: 1.1–1.7) were associated with ICU admission, while age ≥80 years (OR: 4.1, 95% CI: 1.8–12.1) and CHF (OR: 2.4, 95% CI: 1.6–3.6) were associated with in-hospital deaths. RSV-specific ICD codes were listed in the first 9 positions in only 44% (879/1,987) of cases. Conclusion To our knowledge, this is the largest US case series of RSV-infected hospitalized adults. Most cases were ≥65 years and had multiple underlying medical conditions. Older age, CHF, and COPD were associated with the most severe outcomes. Few cases had RSV-specific ICD codes, suggesting that administrative data underestimate adult RSV-related hospitalizations. Continued surveillance is needed to understand the epidemiology of RSV among adults as vaccine products move toward licensure. Disclosures E. J. Anderson, NovaVax: Grant Investigator, Research grant. Pfizer: Grant Investigator, Research grant. AbbVie: Consultant, Consulting fee. MedImmune: Investigator, Research support. PaxVax: Investigator, Research support. Micron: Investigator, Research support. H. K. Talbot, sanofi pasteur: Investigator, Research grant. Gilead: Investigator, Research grant. MedImmune: Investigator, Research grant. Vaxinnate: Safety Board, none. Seqirus: Safety Board, none.