title: Risk of presentation to hospital with epileptic seizures after vaccination with monovalent AS03 adjuvanted pandemic A/H1N1 2009 influenza vaccine (Pandemrix): self controlled case series study.
abstract: OBJECTIVE
  To assess the risk of epileptic seizures in people with and without epilepsy after vaccination with a monovalent AS03 adjuvanted pandemic A/H1N1 influenza vaccine (Pandemrix; Glaxo SmithKline, Sweden).
  
  
  METHODS
  Register based self controlled case series.
  
  
  METHODS
  Three Swedish counties (source population 750,000).
  
  
  METHODS
  373,398 people (age 0-106, median 41.2) who were vaccinated. Vaccinated people with epileptic seizures, diagnosed as inpatients or outpatients, at any time from 90 days before until 90 days after any dose of vaccine.
  
  
  METHODS
  Endpoints were admission to hospital or outpatient hospital care with epileptic seizures as the main diagnosis. The effect estimate of relative incidence was calculated as the incidence of epileptic seizures in period after exposure relative to the incidence of epileptic seizures in two control periods, one before and one after vaccination.
  
  
  RESULTS
  859 people experienced epileptic seizures during the study period. There was no increased risk of seizures in people with previously diagnosed epilepsy (relative incidence 1.01, 95% confidence interval 0.74 to 1.39) and a non-significant decrease in risk for people without epilepsy (0.67, 0.27 to 1.65) during the day 1-7 risk period (where day 1 is the day of vaccination). In a second risk period (day 8-30), there was a non-significant increased risk of seizures in people without epilepsy (1.11, 0.73 to 1.70) but no increase in risk for those with epilepsy (1.00, 0.83 to 1.21).
  
  
  CONCLUSIONS
  This study found no evidence of an increase in risk of presentation to hospital with epileptic seizures after vaccination with a monovalent AS03 adjuvanted pandemic H1N1 influenza vaccine.
authors.affiliation: Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Nobels väg 12A, 171 77 Stockholm, Sweden.
authors.forename: Lisen
authors.initials: L
authors.lastname: Arnheim-Dahlström
authors.forename: Jonas
authors.initials: J
authors.lastname: Hällgren
authors.forename: Caroline E
authors.initials: CE
authors.lastname: Weibull
authors.forename: Pär
authors.initials: P
authors.lastname: Sparén
mesh_terms: D000328:Adult; D000553:Ambulatory Care / Q000706:statistics & numerical data; D016001:Confidence Intervals; D004827:Epilepsy / Q000453:epidemiology / Q000209:etiology; D005260:Female; D006760:Hospitalization / Q000706:statistics & numerical data; D006801:Humans; D015994:Incidence; D053118:Influenza A Virus, H1N1 Subtype / Q000187:drug effects; D007252:Influenza Vaccines / Q000008:administration & dosage / Q000009:adverse effects*; D007251:Influenza, Human / Q000453:epidemiology / Q000517:prevention & control; D008297:Male; D032541:Mass Vaccination / Q000379:methods / Q000706:statistics & numerical data; D058873:Pandemics / Q000517:prevention & control*; D012042:Registries; D018570:Risk Assessment; D012640:Seizures / Q000453:epidemiology / Q000209:etiology; D013548:Sweden / Q000453:epidemiology; D013997:Time Factors
chemical_list: D007252:Influenza Vaccines; C556153:pandemrix