Surveillance studies from several industrialized countries reported an incidence of paediatric hospitalisations associated with seasonal influenza of 11-154/100,000 children < 5 years of age, and an incidence of 1-13/ 100,000 children treated for influenza in paediatric intensive care units (PICUs) [5] [6] [7] . For the influenza season 2003-2004, 153 influenza-associated deaths among children were reported in the United States; 47% of those occurred in children without underlying chronic disease [8] .