1634. Respiratory Syncytial Virus-Associated Health Care Utilization in the Pivotal Phase 3 Trial RSV Vaccine Efficacy Study In Older Adults Immunized Against RSV Disease (RENOIR)

Background Respiratory Syncytial Virus (RSV)-related disease poses an economic burden due to a substantial amount of health care utilization (HCU). RENOIR is a phase 3 global, multicenter, randomized, double-blinded, placebo-controlled study evaluating vaccine efficacy (VE) in adults ≥60 years of age during two RSV seasons in Northern and Southern Hemisphere countries (Argentina, Canada, Finland, Japan, Netherlands, South Africa, and USA) (NCT05035212). VE at the end of the first RSV surveillance season (EOS1) against ARI-RSV, Lower Respiratory Tract Illness (LRTI)-RSV with ≥2 symptoms (2+ LRTI-RSV), and LRTI-RSV with ≥3 symptoms (3+ LRTI-RSV) was 62.2% (44.4, 74.9), 65.1% (35.9, 82.0), and 88.9% (53.6, 98.7), respectively. Methods HCU data and concomitant corticosteroid or antibiotic use were collected during the RSV season for Acute Respiratory Illness (ARI) events (defined as more than 1 day of new or increased cough, nasal congestion/discharge, sore throat, wheezing, sputum production, or shortness of breath). A pre-planned analysis of HCU at EOS1 was performed to assess HCU among participants receiving RSVpreF vs. placebo. Results A higher proportion of RSV-associated HCU was associated with more severe symptoms (43.0%, 60.3%, and 75% for ARI-RSV, 2+ LRTI-RSV, and 3+ LRTI-RSV, respectively). Medically attended (MA) VE was similar to VE for all first-episode cases with MA ARI-RSV 65.1% (35.9, 82.0), MA 2+ LRTI-RSV 70.4% (33.0, 88.4), MA 3+ LRTI-RSV 84.6% (32.0, 98.3). Most RSV-associated HCU were outpatient visits, with more in the placebo arm. A higher proportion of placebo arm participants with RSV cases had an RSV-associated emergency room visit. For ARI-RSV, there were 3 hospitalizations in the placebo arm and none in the RSVpreF arm. The placebo arm had higher antibiotic (11.8 - 55.6% higher) or corticosteroid (2.8 – 44.4% higher) use compared to the RSVpreF arm for ARI- or LRTI-RSV events. Table 1 Vaccine Efficacy of RSVpreF Against First Episode of RSV Cases in the First RSV Season – Evaluable Efficacy Population Table 2 Healthcare Resource Utilization Associated With RSV Cases in the First RSV Season Table 3 Prespecified Category of Concomitant Medication Uses for RSV Cases in the First RSV Season Conclusion RSVpreF reduced overall HCU and antibiotic or corticosteroid treatment for RSV-associated illnesses. The highest VE among MA RSV-associated cases was for MA 3+ LRTI-RSV. These findings suggest that RSVpreF may reduce RSV-related healthcare needs in older adults, thus alleviating this burden on health systems. Disclosures Edward E. Walsh, MD, Icosavax: Advisor/Consultant|Merck: Advisor/Consultant|Merck: Grant/Research Support|Merck: Honoraria|Moderna: Advisor/Consultant|Pfizer: Grant/Research Support Kumar Ilangovan, MD, MSPH, MMCi, Pfizer, Inc.: Employee|Pfizer, Inc.: Stocks/Bonds Agnieszka Zareba, MD PhD, Pfizer: Employee|Pfizer: Stocks/Bonds|Pfizer: Stocks/Bonds Qin Jiang, PhD, Pfizer: Employee|Pfizer: Employee|Pfizer: Stocks/Bonds|Pfizer: Stocks/Bonds Gonzalo Pérez Marc, M.D., GSK: Grant/Research Support|Merck: Grant/Research Support|Moderna: Expert Testimony|Moderna: Grant/Research Support|Pfizer: Grant/Research Support Elliot N. DeHaan, MD, Pfizer: Employee|Pfizer: Stocks/Bonds Michael Patton, B.Sc., Pfizer Inc.: Employee|Pfizer Inc.: Stocks/Bonds Yanqing Kan, MS, Pfizer: Pfizer's employee|Pfizer: Stocks/Bonds Daniel P. Eiras, MD, MPH, Pfizer, Inc.: Stocks/Bonds Tarek Mikati, MD,MPH, Pfizer: Stocks/Bonds Elena Kalinina, PhD, Pfizer: Pfizer employee|Pfizer: Stocks/Bonds David Cooper, PhD, Pfizer, Inc.: Stocks/Bonds Annaliesa S. Anderson, PhD, Pfizer: Employee|Pfizer: Stocks/Bonds Kena A. Swanson, Ph.D., Pfizer: Employee|Pfizer: Stocks/Bonds William C. Gruber, MD, Pfizer, Inc.: Employee|Pfizer, Inc.: Stocks/Bonds Alejandra C. Gurtman, M.D., Pfizer: Employee|Pfizer: Stocks/Bonds Beate Schmoele-Thoma, MD, Pfizer: Stocks/Bonds