Influenza vaccine. Indications in children

Objectives. - To analyze problems related to influenza in children. Initially considered as a disease occurring generally in adults, during the Last few years, it has been established that influenza occurs massively in children. This contributes to the dissemination of the virus in the community. Epidemiology. - Usually influenza has been considered as a nonsevere disease, but it is responsible for many hospitalisations, mainly for infants of less than one year. The probability of hospitalisation is similar to that of adults at risk. Infants' mortality due to influenza is significant. Children with underlying diseases are at risk of hospitalisation as high as in adults. Vaccines. - The majority of available trivalent inactivated vaccines can be used in children. The vaccinal scheme includes two doses separated by one month, as a primovaccination until nine years old in children. Half doses are recommended below three years of age. Tolerance of existing vaccines is considered acceptable but their immunogenicity has not been evaluated. The efficacy of these vaccines has been studied in limited experiments, providing an approximate level of efficacy in about 60% of cases. No data are available regarding demonstration of efficacy in infants of less than two years and those of less than one year. Recommendations. - Vaccinal recommendations vary with countries. In the United States, systematic annual vaccination is recommended in infants of zero to 59 months. This is in contrast with France and practically all European countries, which recommend vaccination in children at risk only. Such a position should be revised provided that efficacy is demonstrated. Protection of the most fragile infants could be obtained by vaccination of persons of their environment. Recommendations of vaccines remain a priority in children at risk, since it remains at the present time a population with a Low level of protection. (c) 2008 Elsevier Masson SAS. Tous droits reserves.