Abstract
BACKGROUND: Respiratory syncytial virus (RSV) vaccines could reduce disease burden and costs in older Canadian adults, but vaccination program cost-effectiveness is unknown. We evaluated the cost-effectiveness of different age cut-offs for RSV adult vaccination programs, with or without a focus on people with higher disease risk due to chronic medical conditions. METHODS: We developed a static individual-based model of medically attended RSV disease to compare alternative age-, medical risk-, and age-plus medical risk-based vaccination policies. The model followed a multiage population of 100 000 people aged 50 years and older. Vaccine characteristics were based on RSV vaccines authorized in Canada as of May 2024, with vaccine protection assumed to last 2 years (or 3 years in scenario analyses). We calculated sequential incremental cost-effectiveness ratios in 2023 Canadian dollars per quality-adjusted life year (QALY) from the health-system and societal perspectives, discounted at 1.5%. RESULTS: Although all vaccination strategies averted medically attended RSV disease, universal age-based strategies were not an efficient use of resources compared with medical risk-based strategies. Vaccinating adults aged 70 years and older with 1 or more chronic medical condition was the optimal strategy for a cost-effectiveness threshold of $50 000 per QALY. Results were sensitive to assumptions about vaccine price, but medical risk-based approaches remained optimal compared with age-based strategies, even when vaccine prices were low. Findings were robust to a range of alternative assumptions. INTERPRETATION: Vaccination programs for RSV in some groups of older Canadians with underlying medical conditions are likely cost-effective. These findings can inform the design of vaccination programs.