Routine influenza vaccination is currently recommended in several countries for people aged more than 60 or 65 years or with high risk of complications. A lower age threshold of 50 years has been recommended in the United States since 1999. To help policymakers consider whether such a policy should be adopted more widely, we conducted an economic evaluation of lowering the age limit for routine influenza vaccination to 50 years in Brazil, France, Germany, and Italy.
The probabilistic model was designed to compare in a single season the costs and clinical outcomes associated with two alternative vaccination policies for persons aged 50 to 64 years: reimbursement only for people at high risk of complications (current policy), and reimbursement for all individuals in this age group (proposed policy). Two perspectives were considered: third-party payer (TPP) and societal. Model inputs were obtained primarily from the published literature and validated through expert opinion. The historical distribution of annual influenza-like illness (ILI) incidence was used to simulate the uncertain incidence in any given season. We estimated gains in unadjusted and quality-adjusted life expectancy, and the cost per quality-adjusted life-year (QALY) gained. Deterministic and probabilistic sensitivity analyses were conducted.
Comparing the proposed to the current policy, the estimated mean costs per QALY gained were R$4,100, 50,000 per QALY gained, the probabilities of the new policy being cost-effective were 94% and 95% for France, 72% and near 100% for Germany, and 89% and 99% for Italy, from the TPP and societal perspectives, respectively.
Extending routine influenza vaccination to people more than 50 years of age is likely to be cost-effective in all four countries studied.