title: Risk of narcolepsy in children and young people receiving AS03 adjuvanted pandemic A/H1N1 2009 influenza vaccine: retrospective analysis.
abstract: OBJECTIVE
  To evaluate the risk of narcolepsy in children and adolescents in England targeted for vaccination with ASO3 adjuvanted pandemic A/H1N1 2009 vaccine (Pandemrix) from October 2009.
  
  
  METHODS
  Retrospective analysis. Clinical information and results of sleep tests were extracted from hospital notes between August 2011 and February 2012 and reviewed by an expert panel to confirm the diagnosis. Vaccination and clinical histories were obtained from general practitioners.
  
  
  METHODS
  Sleep centres and paediatric neurology centres in England.
  
  
  METHODS
  Children and young people aged 4-18 with onset of narcolepsy from January 2008.
  
  
  METHODS
  The odds of vaccination in those with narcolepsy compared with the age matched English population after adjustment for clinical conditions that were indications for vaccination. The incidence of narcolepsy within six months of vaccination compared with the incidence outside this period measured with the self controlled cases series method.
  
  
  RESULTS
  Case notes for 245 children and young people were reviewed; 75 had narcolepsy (56 with cataplexy) and onset after 1 January 2008. Eleven had been vaccinated before onset; seven within six months. In those with a diagnosis by July 2011 the odds ratio was 14.4 (95% confidence interval 4.3 to 48.5) for vaccination at any time before onset and 16.2 (3.1 to 84.5) for vaccination within six months before onset. The relative incidence from the self controlled cases series analysis in those with a diagnosis by July 2011 with onset from October 2008 to December 2010 was 9.9 (2.1 to 47.9). The attributable risk was estimated as between 1 in 57,500 and 1 in 52,000 doses.
  
  
  CONCLUSIONS
  The increased risk of narcolepsy after vaccination with ASO3 adjuvanted pandemic A/H1N1 2009 vaccine indicates a causal association, consistent with findings from Finland. Because of variable delay in diagnosis, however, the risk might be overestimated by more rapid referral of vaccinated children.
authors: Immunisation, Hepatitis and Blood Safety Department, Health Protection Agency, Colindale, London NW9 5EQ, UK. liz.miller@hpa.org.uk
authors: Elizabeth
authors: E
authors: Miller
authors: Nick
authors: N
authors: Andrews
authors: Lesley
authors: L
authors: Stellitano
authors: Julia
authors: J
authors: Stowe
authors: Anne Marie
authors: AM
authors: Winstone
authors: John
authors: J
authors: Shneerson
authors: Christopher
authors: C
authors: Verity
mesh_terms: D000276:Adjuvants, Immunologic / Q000009:adverse effects; D000293:Adolescent; D002648:Child; D002675:Child, Preschool; D004739:England / Q000453:epidemiology; D005260:Female; D006801:Humans; D015994:Incidence; D053118:Influenza A Virus, H1N1 Subtype / Q000276:immunology*; D007252:Influenza Vaccines / Q000009:adverse effects*; D008297:Male; D009290:Narcolepsy / Q000453:epidemiology* / Q000209:etiology; D016017:Odds Ratio; D012189:Retrospective Studies
chemical_list: D000276:Adjuvants, Immunologic; D007252:Influenza Vaccines; C556153:pandemrix