The burden of influenza in children under 5 years admitted to the Children's Hospital at Westmead in the winter of 2006

Abstract

Active surveillance to determine influenza disease burden in children admitted to hospital with influenza-like illness (ILI). A prospective hospital-based cohort study conducted June-October 2006 in children <5 years hospitalised at The Children's Hospital at Westmead with ILI (fever and respiratory symptoms). Influenza and other viral infections were diagnosed either by antigen detection using immunofluorescence or nucleic acid amplification testing of nasopharyngeal aspirates. Data were collected using researcher-administered questionnaires. Main outcome measures include proportion of hospitalisations with influenza, vaccination and treatment, risk factors for influenza and associated medical and social burdens. Data on 275 children with ILI aged <5 years were analysed. Thirty-one (11%) children with ILI had influenza (22 had influenza A and 9 had influenza B). Thirty-five percent were under 6 months of age and 61% under 1 year. Twenty-nine percent of children with influenza A were born prematurely. The mean duration of hospital stay for influenza was 2.8 days (95% confidence interval 2.1-3.4) and 26% had a lumbar puncture. Although 68% received intravenous antibiotics, only 3% (one case) was given an antiviral. Eighty-four percent had visited their local doctor before admission and all came through the emergency department. On average, in one-third (32%) of families of children with influenza a parent developed, ILI during admission or soon after hospital discharge resulted in an average of 3.2 days of work absenteeism. Only 3.5% (7/199) of children older than 6 months with ILI received any influenza vaccination. Both the burden of influenza in childhood morbidity and its social impact are substantial. There is considerable room for improvement in both the prevention and early recognition (trigger treatment with antivirals) of influenza. Our data will inform decisions regarding the value of a universal influenza vaccine programme.