Résumé
In France, the flu causes a heavy burden on both the healthcare system and society, with millions of doctor visits and thousands of hospital stays every year. Current vaccine guidelines mainly target those aged 65 and above; however, people over 50 often have other health problems and should be considered at a higher risk. Our study explored what might happen if the vaccine were offered to everyone aged 50 and older. We gathered data from published research and French health insurance records to build a model that simulates how the virus spreads and affects different age groups. We compared the current vaccination practice with several strategies that extend vaccination to people aged 50 and above. Our findings show that expanding vaccination could reduce doctor visits by more than 500,000, cut hospital admissions by almost 10,000, and prevent nearly 3000 deaths, at an additional cost of about 58 million euros. When we considered savings from reduced lost work and other indirect costs, the strategy not only paid for itself but also saved money overall. This analysis suggests that vaccinating more adults could be a cost-effective and life-saving public health measure.