A large number of papers are regularly published about anti-flu vaccine with discordant results regarding their efficacy. Through a recent review the efficacy of the vaccine has been evaluated both in terms of the immune response, the protection against clinical disease, but also as regards the impact from an epidemiological and economic point of view. In the majority of papers in which the immune response was studied before and after vaccination a 60 to 100% case of protection was obtained serologically by measuring the protective antibodies. These levels varied as a function of the type of the vaccination (inactive or living) and also of the immune state of the subject. In subjects of more than 60 years of age the immune response was 1.5 to 2 times less that in the young adult. The protection against clinical disease in children and adults is of the order of 40 to 70%, according to whether the infection is confirmed or not. On the other hand the vaccine is less effective in the elderly subjects, but gives a protection of the order of 75% protection against complications or of mortality linked to influenza. Finally there are a certain number of epidemiological and economic arguments which would justify the vaccine use on a large scale.