Assessing the Cost-Effectiveness of an mRNA-Based Rsv Vaccine (mRNA-1345) Amongst Canadian Adults Aged ≥60 Years

OBJECTIVES: Respiratory syncytial virus (RSV) infection is a leading cause of lower respiratory tract disease (LRTD), mortality, and health system expenditure amongst older Canadian adults.¹ An mRNA-based RSV vaccine, mRNA-1345, has demonstrated efficacy against RSV-LTRD and RSV-acute respiratory tract disease (ARD).² This study estimated the cost-effectiveness of vaccination with a single dose of mRNA-1345, versus no vaccination, amongst ≥60-year-old Canadians from a public health payer perspective.

METHODS: We constructed a static cohort-based, decision-tree to estimate the RSV-related events, and corresponding economic impacts by treatment setting, expected for each strategy. We modeled outcomes over the mRNA-1345 pivotal phase 3 trial duration (24 months) and discounted the loss of life-expectancy due to RSV-related mortality over the entire lifespan to present value. We obtained input values through calibration (e.g., age-specific targets: 62.4-328.1 hospitalizations per 100,000), and from published studies (e.g., RSV incidence: 6.7%, age-dependent RSV-mortality: 7.6%-14.0%, RSV-hospitalization cost: $43,074/year).^3-5 Vaccine coverage ranged by age (43-73%) per Canadian national influenza immunization rates.⁶ The protective effects of mRNA-1345 against RSV-ARD, RSV-LRTD, and associated hospitalizations, were adjusted by Canadian seasonality data and waned over 24 months.⁷ Costs (2023 CAD dollars) and outcomes were discounted by 1.5%. The expected incremental cost-effectiveness ratio (ICER) was calculated using probabilistic analysis.

RESULTS: Compared to no vaccination, mRNA-1345 was $882,116,101 more costly, saved 13,195 extra life-years, and yielded 18,333 additional quality-adjusted life-years (QALYs). Based on the corresponding ICER of $48,118/QALY gained, mRNA-1345 represents a cost-effective strategy at a $50,000/QALY willingness-to-pay threshold. Immunization could prevent, during a 24-month follow-up, 331,372 RSV-ARD cases (including 94,968 RSV-LRTD cases), 15,207 RSV-related hospitalizations, and 1,663 deaths. Model results are most sensitive to RSV-ARD incidence, QALY loss modelled for outpatient care and no treatment, and hospitalization rate calibration targets.

CONCLUSIONS: At the willingness-to-pay threshold of $50,000/QALY, mRNA-1345 is a cost-effective intervention for reducing RSV-LRTD, RSV-associated mortality and healthcare resource use.