Influential drivers of the cost-effectiveness of respiratory syncytial virus vaccination in European older adults: A multi-country analysis

Background: We aimed to identify influential drivers of the cost-effectiveness of older adult respiratory syncytial virus (RSV) vaccination in Denmark, Finland, the Netherlands and Valencia-Spain. Methods: A static multi-cohort model was parameterised using country- and age-specific hospitalisations using three approaches: (1) the International Classification of Diseases (ICD)-coded hospitalisations, (2) laboratory RSV-confirmed hospitalisations and (3) time-series modelling (TSM). Plausible hypothetical RSV vaccine characteristics were derived from two protein subunit vaccines for adults aged greater than 60 years (60y+). Costs and quality-adjusted life-years (QALYs) were compared between four strategies: (a) no intervention, and RSV vaccination in adults (b) 60y+; (c) 65y+; (d) 75y+, from both the healthcare payers and societal perspectives. Value of information, probabilistic sensitivity and scenario analyses identified influential drivers. Results: Besides vaccine price, the hospitalisation estimates were most influential: Using adjusted RSV-ICD-coded hospitalisations at a vaccine price of EUR150 per dose, no intervention was cost-effective up to willingness-to-pay (WTP) values of EUR 80 000 per QALY gained in Denmark, and up to EUR 34 000 and EUR 62 000 per QALY gained in Finland and the Netherlands, respectively. Using the adjusted RSV-confirmed dataset, the findings were consistent in Denmark and comparable in Finland. In Spain-Valencia, the 75y+ strategy became cost-effective at WTP > EUR 17 000. Using TSM-based estimates, the 75y+ strategy was cost-effective at WTP > EUR 16 000, > EUR 28 000, >EUR 13 000 and >EUR 37 000 in Denmark, Finland, the Netherlands and Spain-Valencia, respectively. The (in-hospital) case fatality ratio and the specification of its age dependency were both influential. Specifying different ways in which protective efficacy waned and RSV seasons were shaped and timed had both relatively limited impact on results. Conclusion: Data gaps and uncertainties on the RSV-related burden in older adults persists and influences the cost-effectiveness of RSV vaccination. More refined age- and country-specific data on the RSV attributable burden are crucial to aid decision making.