title: The burden of influenza in England by age and clinical risk group: a statistical analysis to inform vaccine policy.
abstract: OBJECTIVE
  To assess the burden of influenza by age and clinical status and use this to inform evaluations of the age and risk-based influenza vaccination policy in the United Kingdom.
  
  
  METHODS
  Weekly laboratory reports for influenza and 7 other respiratory pathogens were extracted from the national database and used in a regression model to estimate the proportion of acute respiratory illness outcomes attributable to each pathogen.
  
  
  RESULTS
  Influenza accounted for ∼10% of the attributed respiratory admissions and deaths in hospital. Healthy children under five had the highest influenza admission rate (1.9/1000). The presence of co-morbidities increased the admission rate by 5.7 fold for 5-14 year olds (from 0.1 to 0.56/1000), the relative risk declining to 1.8 fold in 65+ year olds (from 0.46 to 0.84/1000). The majority (72%) of influenza-attributable deaths in hospital occurred in 65+ year olds with co-morbidities. Mortality in children under 15 years was low with around 12 influenza-attributable deaths in hospital per year in England; the case fatality rate was substantially higher in risk than non-risk children. Infants under 6 months had the highest consultation and admission rates, around 70/1000 and 3/1000 respectively.
  
  
  CONCLUSIONS
  Additional strategies are needed to reduce the remaining morbidity and mortality in the high-risk and elderly populations, and to protect healthy children currently not offered the benefits of vaccination.
authors.affiliation: Complex Systems in Biology Group, Centre for Vascular Research, University of New South Wales, Sydney, Australia. Electronic address: d.cromer@unsw.edu.au.
authors.forename: Deborah
authors.initials: D
authors.lastname: Cromer
authors.affiliation: Public Health England, London, United Kingdom.
authors.forename: Albert Jan
authors.initials: AJ
authors.lastname: van Hoek
authors.affiliation: Public Health England, London, United Kingdom; Department of Infectious Disease Epidemiology, London School of Hygiene and Tropical Medicine, London, United Kingdom.
authors.forename: Mark
authors.initials: M
authors.lastname: Jit
authors.affiliation: Department of Infectious Disease Epidemiology, London School of Hygiene and Tropical Medicine, London, United Kingdom.
authors.forename: W John
authors.initials: WJ
authors.lastname: Edmunds
authors.affiliation: Research and Surveillance Unit, Royal College of General Practitioners, Birmingham, United Kingdom.
authors.forename: Douglas
authors.initials: D
authors.lastname: Fleming
authors.affiliation: Public Health England, London, United Kingdom.
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Miller
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D002675:Child, Preschool; D004739:England / Q000453:epidemiology; D005260:Female; D006291:Health Policy; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D007252:Influenza Vaccines / Q000008:administration & dosage*; D007251:Influenza, Human / Q000453:epidemiology* / Q000401:mortality / Q000517:prevention & control*; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D012307:Risk Factors; D016019:Survival Analysis; D055815:Young Adult
chemical_list: D007252:Influenza Vaccines
keywords: Disease burden; Influenza; Modelling; Policy; Regression; Vaccination