Outbreaks of influenza and influenza-like illness in schools in England and Wales, 2005/06

In England and Wales, clinical reports from primary care showed that influenza activity for the season 2005/06 only rose above the base line for four weeks during February 2006. However, outbreaks of influenza-like illness and/or gastrointestinal infection in schools began to be reported to the Health Protection Agency, Centre for Infections in early January 2006. To quantify the type, size and the spread of these outbreaks a reporting form was distributed to local Health Protection Units in England and to Wales for retrospective and prospective weekly completion. Between weeks 48/05 and 11/06, a total of 688 school outbreaks were reported, including 658 outbreaks of influenza-like illness with or without other symptoms. The remaining 30 outbreaks listed as gastrointestinal only were excluded from the present analysis. Influenza B was confirmed in 70 outbreaks where testing took place. 61% of the outbreaks were reported from primary schools for children aged 4-11 years. This large scale outbreak in school children with flu-like illness across England and Wales was not picked up by most of the routine surveillance schemes, therefore, we believe that a school absentee monitoring and reporting system may be needed to give an early warning of increased influenza activity, especially for the mild form of the disease caused by influenza B virus.