Influenza-related hospitalisations among children aged less than 5 years old in the Basque Country, Spain: a 3-year study (July 2001-June 2004).

This population-based study evaluated the incidence of virologically confirmed influenza-related hospitalisation in children aged <5 years between July 2001 and June 2004 in a region of southern Europe. Forty-nine children with influenza virus infection were hospitalised. The annual hospitalisation rates per 1000 inhabitants for each period were 5.1, 0 and 7.3 for infants aged less than 6 months, 0.9, 0.2 and 0.9 for children aged 6-23 months, and 0.7, 0.1 and 0.8 for those aged 24-59 months. Most of the children were hospitalised in the epidemic waves caused by the influenza A/H3N2 virus and were previously healthy. This study supports the need to introduce measures to reduce the burden of disease due to influenza virus infection in young children. New vaccines or vaccination strategies that could be applied in infants should be developed.