Clinical manifestations and socio-economic impact of influenza among healthy children in the community.

Objectives: To evaluate the total burden of influenza among healthy children in the community in order to analyse the cost of influenza in paediatric age.

Methods: This prospective study involved a total community population of 21,986 children, 6988 of whom experienced an influenza-like illness (ILI) between 1 November 2008 and 30 April 2009. An electronic chart was completed, a nasopharyngeal swab was obtained, and information was recorded concerning the clinical outcomes and household impact of the ILI episodes. Influenza A and B viruses were detected in all the swabs by means of polymerase chain reaction, and costs of the disease were calculated.

Results: Influenza viruses were detected in 2143 cases (30.7%), an incidence of 96.4 per 1000 children. Influenza A and B viruses were found in respectively 1751 (81.7%) and 392 cases (18.3%). The mean cost of influenza was no less than €130, 32% higher than the cost of influenza-negative ILIs (p < 0.001). The influenza A cases were significantly more expensive than the influenza B cases (p < 0.001), and influenza in children aged <2 and 2-5 years was significantly more expensive than in children aged >5 years (p < 0.05). The differences were mainly related to the indirect costs of the parents' lost working days.

Conclusions: The findings of this study confirm that influenza among healthy children is important because of its frequency and its indirect consequences on the households of infected children, and support the use of influenza vaccination in healthy children aged between 6 months and 5 years.