title: Association between type 1 diabetes and Haemophilus influenzae type b vaccination: birth cohort study.
abstract: OBJECTIVE
  To determine the effect of Haemophilus influenzae type b vaccination and its timing on the risk of type 1 diabetes in Finnish children.
  
  
  METHODS
  Cumulative incidence and relative risk of type 1 diabetes was compared among three birth cohorts of Finnish children: those born during the 24 months before the H influenzae type b vaccination trial, those in the trial cohort who were vaccinated at 3 months of age and later with a booster vaccine, and those in the trial cohort who were vaccinated at 24 months of age only. The probability of type 1 diabetes was estimated using regression analysis assuming that there were no losses to 10 year follow up and no competing risks.
  
  
  METHODS
  Finland (total population 5 million and annual birth rate 1.3%).
  
  
  METHODS
  128 936 children born from 1 October 1983 to 1 September 1985, and 116 352 children born from 1 October 1985 to 31 August 1987.
  
  
  METHODS
  Probability of type 1 diabetes among children vaccinated with H influenzae type b and non-vaccinated children.
  
  
  RESULTS
  No statistically significant difference was found at any time during the 10 year follow up in the risk of type 1 diabetes between the children born before the vaccination period and those vaccinated at the age of 24 months only (relative risk 1.01). The difference in the risk between the cohort vaccinated first at the age of 3 months and the cohort vaccinated at the age of 24 months only was not statistically significant either (1.06).
  
  
  CONCLUSIONS
  It is unlikely that H influenzae type b vaccination or its timing cause type 1 diabetes in children.
authors.affiliation: Diabetes and Genetic Epidemiology Unit, National Public Health Institute, Mannerheimintie 166, FIN-00300 Helsinki, Finland. Marjatta.karvonen@ktl.fi
authors.forename: M
authors.initials: M
authors.lastname: Karvonen
authors.forename: Z
authors.initials: Z
authors.lastname: Cepaitis
authors.forename: J
authors.initials: J
authors.lastname: Tuomilehto
mesh_terms: D000367:Age Factors; D002648:Child; D002675:Child, Preschool; D015331:Cohort Studies; D003922:Diabetes Mellitus, Type 1 / Q000209:etiology*; D004168:Diphtheria Toxoid / Q000009:adverse effects*; D005387:Finland / Q000453:epidemiology; D018073:Haemophilus Vaccines / Q000009:adverse effects*; D006801:Humans; D015994:Incidence; D007223:Infant; D007231:Infant, Newborn; D012307:Risk Factors; D014611:Vaccination / Q000009:adverse effects
chemical_list: D004168:Diphtheria Toxoid; D018073:Haemophilus Vaccines; C052180:Haemophilus influenzae type b-polysaccharide vaccine-diphtheria toxoid conjugate