Cost-Effectiveness of Alternative Immunization Strategies to Protect Infants Against Respiratory Syncytial Virus in Germany: A Decision Modeling Study

INTRODUCTION: Germany's Standing Committee on Vaccination (STIKO) recommends the use of monoclonal antibody nirsevimab for infants in their first respiratory syncytial virus (RSV) season; however, incorporating RSVpreF maternal vaccination may protect more infants while lowering healthcare costs. We therefore evaluated the cost-effectiveness of a complementary immunization approach comprising maternal RSVpreF vaccination during pregnancy and nirsevimab for infants not yet protected to prevent lower respiratory tract disease due to RSV (RSV-LRTD) among infants in Germany. METHODS: Clinical and economic outcomes of RSV-LRTD and the expected impact of interventions were modeled from birth to age < 1 year. Model inputs were based on German data as available. Intervention strategies included no intervention, nirsevimab alone (N-all; uptake 70%), and the complementary immunization approach (MV + N). MV + N comprised seasonally administered maternal vaccination (MV; uptake 50%) with nirsevimab (N; uptake 70%) for unprotected infants (MV + N). Nirsevimab was administered seasonally with catch-up for infants born outside the RSV season. Analyses were conducted from the societal perspective and discounted 3% annually. RESULTS: Without immunization, 70,041 cases of RSV-LRTD (hospital: 23,273, ambulatory: 46,768) and 22 deaths were projected; total RSV-attributable medical care costs were 118.6 million (M) €. With N-all, there were 39,247 cases (hospital 12,953; ambulatory 26,294) and 13 deaths; total associated costs were 311.5M € (intervention 237.2M €; medical care 66.0M €; indirect 8.4M €). Compared to N-all, MV + N prevented an additional 666 cases and 1 death, with a difference in total costs of - 17.8M € (intervention - 12.7M €; medical care - 4.7M €; indirect - 0.4M €). With 31 QALYs gained, MV + N was dominant versus N-All. CONCLUSION: A complementary strategy with maternal RSVpreF vaccination and nirsevimab immunization for otherwise unprotected and preterm infants in Germany would provide a greater benefit compared to nirsevimab alone, protecting substantially more infants at lower total costs.