Cost-Effectiveness of Nirsevimab and Clesrovimab in Preventing Respiratory Syncytial Virus Lower Respiratory Tract Disease in Infants in the United States: A Modeling Study.

introductionRespiratory syncytial virus (RSV) is the leading cause of infant hospitalizations in the United States, with a significant seasonal impact on healthcare resources. Long-acting monoclonal antibodies (mAbs), nirsevimab and clesrovimab, provide protection against RSV-related lower respiratory tract disease (LRTD); however, no head-to-head comparisons are available to inform clinical decision-making.

methodsWe developed a cost-effectiveness analysis framework to perform an indirect comparison of nirsevimab and clesrovimab for RSV prevention, consistent with CDC guidance for pre-season catch-up and in-season immunization for infants born outside and during the RSV season, respectively. Pharmacokinetic data were used to model the duration of cumulative efficacy over time. A 150-day duration was evaluated for nirsevimab, while three scenarios were assessed for clesrovimab (100-, 120-, and 150-day durations). A cost-utility analysis evaluated health outcomes, healthcare resource use, and associated costs.

resultsThe modeled prediction suggests nirsevimab demonstrated greater clinical benefit and more favorable economic outcomes compared to clesrovimab across all protection duration scenarios. Nirsevimab use consistently resulted in reduced cases of RSV medically attended (MA)-LRTDs and therefore direct and indirect costs associated with RSV management. From a cost-effectiveness perspective, nirsevimab was dominant (i.e., more effective and less costly) compared to clesrovimab in all analyzed scenarios. Additional scenario analyses leveraging trial data differentiated by infant gestational age for both nirsevimab and clesrovimab and alternative RSV seasonality demonstrated that model conclusions remain stable. These analyses confirmed the robustness of our findings, with nirsevimab consistently offering greater value.

conclusionsOur findings predict that nirsevimab is economically dominant over clesrovimab while providing greater clinical protection against RSV-related disease in these scenarios. These results are robust to sensitivity analyses with nirsevimab consistently estimated as reducing healthcare resource utilization and total costs compared to clesrovimab across assumptions related to clesrovimab duration of cumulative efficacy as well as variation in key model parameters.