Cost-Effectiveness Analysis of Expanding Influenza Vaccination to Adults Aged 50 and Over in France

Influenza in France causes, on average, more than 1 million primary care consultations, 20,000 hospitalizations, and 9000 deaths annually. Adults over 50 years of age face higher risks of severe influenza due to increasing chronic conditions associated with aging, yet vaccination rates in this group are low, as recommendations start from age 65. This study explores the potential health and economic benefits of expanding vaccination recommendations to individuals aged 50 and over.

Using the literature and French health insurance data, a SEIR (susceptible-exposed-infectious-recovered) model was developed. The subpopulations were stratified by age, vaccination status, and risk profile. Various expanded vaccination strategies were compared to the current strategy, assessing impacts on epidemiological outcomes (consultations, hospitalizations, deaths), economic metrics (vaccination costs, medical care expenses), and quality-adjusted life years (QALY). The model's robustness was tested with deterministic and probabilistic sensitivity analyses.

Expanded vaccination recommendations for individuals over 50 years of age lead to an average reduction of 500,124 consultations, 9486 hospitalizations, and 2990 deaths, with an associated additional cost of 58 million euros compared to the current vaccination strategy. The cost-effectiveness analysis estimates an incremental cost-effectiveness ratio (ICER) of €1496/QALY. When considering indirect costs, the total savings in this expanded vaccination scenario amount to €- 314,308,377, resulting in a dominant ICER. This indicates that the strategy would not only be more cost-effective but also cost-saving compared to the current approach.

Expanding vaccination recommendations for low-risk adults over 50 is cost-effective and represents a significant public health opportunity.