Respiratory syncytial virus vaccination strategies for older Canadian adults: a cost-utility analysis

Background: Vaccines against respiratory syncytial virus (RSV) have the potential to reduce disease burden and costs in Canadians, but the cost-effectiveness of RSV vaccination programs for older adults is unknown. We evaluated the cost-effectiveness of different adult age cutoffs for RSV vaccination programs, with or without a focus on people with higher disease risk due to chronic medical conditions (CMCs). Methods: We developed a static individual-based model of medically-attended RSV disease to evaluate the cost-utility of alternate age-, medical risk-, and age- plus medical risk-based vaccination policies. The model followed a multi-age cohort of 100,000 people aged 50 years and older over a three-year period. Vaccine characteristics were based on RSV vaccines authorized in Canada as of March 2024. We calculated incremental cost-effectiveness ratios (ICERs) in 2023 Canadian dollars per quality-adjust life year (QALY) from the health system and societal perspectives, discounted at 1.5%. Results: Although all vaccination strategies averted medically-attended RSV disease, strategies focused on adults with CMCs were more likely to be cost-effective than age-based strategies. A program focused on vaccinating adults aged 70 years and older with one or more CMCs was optimal for a cost-effectiveness threshold of $50,000 per QALY. Results were sensitive to assumptions about vaccine price, but approaches based on medical risk remained optimal compared to age-based strategies even when vaccine prices were low. Findings were robust to a range of alternate assumptions. Interpretation: Based on available data, RSV vaccination programs in some groups of older Canadians with underlying medical conditions are expected to be cost-effective.