Valutazione economica del vaccino antinfluenzale adiuvato con virosomi in Italia nella popolazione anziana

According to WHO, seasonal influenza affects 5–15% of population. Its burden (hospitalizations and deaths) is particularly heavy on elderly people. The only effective means of combating influenza is vaccination, and adjuvanted vaccines optimize the immune response. This work aims at evaluating the economic convenience of a virosomal vaccine in preventing hospitalization for influenza and pneumonia in the elderly in Italy; it is designed as a cost-benefit analysis, comparing vaccination costs with corresponding savings from hospitalization reduction. The analysis is based on a published case-control study performed in the elderly population (>64 years) residing in Genoa (Italy). The study period was the 2010–2011 season. A 95.2% vaccine effectiveness (p=0.004) was estimated. The present analysis is conducted from the perspective of the National Health Service, at the whole country level. The vaccine cost was evaluated at discounted price and the hospitalizations with a weighted DRG tariff. Assuming to treat with a virosomal vaccine the Italian elderly population not covered (42%, i.e. 5,166,646 people), the campaign would cost €84.4 million (of which one third due to the cost of vaccine). Coeteris paribus, this strategy would prevent 41,280 hospitalizations, with savings amounting to €121.9 million—giving a net benefit of €37.5 million. A one-way sensitivity analysis (exploring: the uncertainty around the vaccine effectiveness; the herd immunity effect; a 75% coverage of the elderly population, corresponding to the Italian Ministry of Health target) substantially confirmed the favourable base case result, with net benefits ranging from −€4 million to €47.5 million.