P-650. Cost-Effectiveness Analysis of Clesrovimab for Protection against Infant Respiratory Syncytial Virus Disease in the United States

Abstract Background Respiratory syncytial virus (RSV) causes significant hospitalization burden. Clesrovimab is an investigational, long-acting monoclonal antibody in development for the prevention of RSV lower respiratory tract infection in infants. The objective of this study was to evaluate the cost-effectiveness of introducing clesrovimab in US infants born during or entering their first RSV season.Figure 1Number of MALRI estimated for (blue) palivizumab, (orange) RSVpreF, (grey) nirsevimab, and (yellow) clesrovimab.Figure 2Economic impact of (blue) palivizumab, (orange) RSVpreF, (grey) nirsevimab, and (yellow) clesrovimab. Methods A decision tree model simulated the clinical and economic impact of clesrovimab in infants, compared with three alternative interventions: nirsevimab, palivizumab, and RSVpreF vaccine. Model inputs were obtained from published literature. Efficacy estimate for clesrovimab resulted from a post-hoc analysis of the trial data, which was conducted to align endpoints from different studies. Health outcomes and costs (in 2024 USD) were evaluated from a societal perspective. Both deterministic and probabilistic sensitivity analyses were performed. Various efficacy assumptions were examined as scenario analyses. Results Figures 1 and 2 illustrate the clinical and economic impacts of palivizumab, RSVpreF, nirsevimab, and clesrovimab. Clesrovimab resulted in fewer RSV-related medically attended lower respiratory infection (MALRI) outcomes and was cost-saving compared to nirsevimab, with significant reductions in total MALRI costs ranging from $33 million to $161 million. When compared to palivizumab and RSVpreF, clesrovimab was estimated to cost between $7,372–$42,691 and $79,366–$134,353 per quality-adjusted life year (QALY), respectively. Results were sensitive to changes regarding intervention cost-per-dose parameters, efficacy assumptions, and QALY loss due to RSV infection. Conclusion Based on listed parameters a single dose of clesrovimab can significantly reduce the burden of RSV among US infants and lead to cost-savings compared to nirsevimab. Disclosures Klodeta Kura, PhD, MSD: Stocks/Bonds (Private Company) John C. Lang, PhD, MSc, MSc, BSc, Merck Canada Inc.: Stocks/Bonds (Private Company) Dawei Wang, PhD, Merck: Stocks/Bonds (Private Company) Yoonyoung Choi, PhD, MS, RPh, Merck & Co., Inc.: Grant/Research Support|Merck & Co., Inc.: Employment|Merck & Co., Inc.: Stocks/Bonds (Private Company) Michelle Goveia, MD, Merck: Stocks/Bonds (Private Company) Anushua Sinha, MD, Merck & Co., Inc., Rahway, NJ, USA: Employment|Merck & Co., Inc., Rahway, NJ, USA: Stocks/Bonds (Public Company) Yao-Hsuan Chen, PhD, MSD: Stocks/Bonds (Private Company) Elamin Elbasha, Ph.D., Merck & Co., Inc.: Employee|Merck & Co., Inc.: Stocks/Bonds (Public Company)