Cost-benefit evaluation of anti-influenza vaccination in the elderly during two influenza seasons in the Siena district [Valutazione benefici-costi della vaccinazione antinfluenzale negli anziani in due stagioni epidemiche a confronto nella provincia di Siena]

Objective: To carry out a survey on anti-influenza vaccination coverage and effectiveness in elderly people, and to evaluate its cost-benefit ratio. Design and methods: We performed a cost-benefit analysis based on direct costs. A survey was carried out by means of a questionnaire (filled by General Practitioners with reference to a selected sample of elderly) during two different influenza seasons: 1999/2000 (characterised by an average epidemic), and 2000/2001 (small epidemic). Subjects were asked to provide info about personal data, vaccination status (including related costs) and (if they had got the flu) disease characteristics (i.e. drugs used, visits, hospitalisation). A unit cost was applied to the resources used. Results: A total of 496 subjects aged > 65 years responded in the first influenza season and 501 in the second. The cost-benefit ratio in the vaccinated population was 4.63 in the first season vs 3.58 in the second. Therefore, the saving for every vaccinated person was Lit. 93,167.6 and Lit. 70,738.3, respectively. Conclusions: The cost/benefit ratio was higher in the average epidemic season than in the low epidemic season because of the higher influenza incidence and the greater efficacy of vaccination (i.e. a greater number of prevented cases). Influenza vaccination seems to be advantageous in terms of cost-effectiveness and cost-benefit ratios, thus justifying the objective of reaching the highest possible coverage in elderly people.