title: Vaccine Safety Datalink project: a new tool for improving vaccine safety monitoring in the United States. The Vaccine Safety Datalink Team.
abstract: OBJECTIVE
  To fill the large "gaps and limitations" in current scientific knowledge of rare vaccine adverse events identified in recent reviews of the Institute of Medicine.
  
  
  METHODS
  Computerized information on immunization, medical outcomes, and potential confounders on more than 500 000 children 0 to 6 years of age is linked annually at several health maintenance organizations to create a large cohort for multiple epidemiologic studies of vaccine safety.
  
  
  RESULTS
  Analysis of 3 years of follow-up data shows that 549 488 doses of diphtheria-tetanus-pertussis (DTP) and 310 618 doses of measles-mumps-rubella (MMR) vaccines have been administered to children in the study cohort. Analyses for associations between vaccines and 34 medical outcomes are underway. Screening of automated data shows that seizures are associated with receipt of DTP on the same day (relative risk [RR], 2.1; 95% confidence interval [CI], 1.1 to 4.0) and 8 to 14 days after receipt of MMR (RR, 3.0; 95% CI, 2.1 to 4.2). The diversity of vaccination exposures in this large cohort permits us to show that an apparent association of seizures 8 to 14 days after Haemophilus influenzae type b vaccine (RR, 1.6; 95% CI, 1.2 to 2.1) was attributable to confounding by simultaneous MMR vaccination; the association disappears with appropriate adjustment (RR, 1.0; 95% CI, 0.7 to 1.4).
  
  
  CONCLUSIONS
  Preliminary design, data collection, and analytic capability of the Vaccine Safety Datalink project has been validated by replication of previous known associations between seizures and DTP and MMR vaccines. The diversity in vaccine administration schedules permits potential disentangling of effects of simultaneous and combined vaccinations. The project provides a model of public health-managed care collaborations in addition to an excellent infrastructure for safety and other studies of vaccines.
authors.affiliation: National Immunization Program, Centers for Disease Control and Prevention, Atlanta, Georgia 30333, USA.
authors.forename: R T
authors.initials: RT
authors.lastname: Chen
authors.forename: J W
authors.initials: JW
authors.lastname: Glasser
authors.forename: P H
authors.initials: PH
authors.lastname: Rhodes
authors.forename: R L
authors.initials: RL
authors.lastname: Davis
authors.forename: W E
authors.initials: WE
authors.lastname: Barlow
authors.forename: R S
authors.initials: RS
authors.lastname: Thompson
authors.forename: J P
authors.initials: JP
authors.lastname: Mullooly
authors.forename: S B
authors.initials: SB
authors.lastname: Black
authors.forename: H R
authors.initials: HR
authors.lastname: Shinefield
authors.forename: C M
authors.initials: CM
authors.lastname: Vadheim
authors.forename: S M
authors.initials: SM
authors.lastname: Marcy
authors.forename: J I
authors.initials: JI
authors.lastname: Ward
authors.forename: R P
authors.initials: RP
authors.lastname: Wise
authors.forename: S G
authors.initials: SG
authors.lastname: Wassilak
authors.forename: S C
authors.initials: SC
authors.lastname: Hadler
mesh_terms: D016907:Adverse Drug Reaction Reporting Systems; D001426:Bacterial Proteins / Q000009:adverse effects; D002648:Child; D002675:Child, Preschool; D003625:Data Collection; D015721:Diphtheria-Tetanus-Pertussis Vaccine / Q000009:adverse effects; D018073:Haemophilus Vaccines / Q000009:adverse effects; D006279:Health Maintenance Organizations; D006801:Humans; D007223:Infant; D007256:Information Systems; D008458:Measles Vaccine / Q000009:adverse effects; D022542:Measles-Mumps-Rubella Vaccine; D009108:Mumps Vaccine / Q000009:adverse effects; D016730:Program Development; D011786:Quality Control; D012306:Risk; D012411:Rubella Vaccine / Q000009:adverse effects; D012640:Seizures / Q000139:chemically induced; D014481:United States; D014612:Vaccines / Q000009:adverse effects*; D017778:Vaccines, Combined / Q000009:adverse effects
chemical_list: D001426:Bacterial Proteins; D015721:Diphtheria-Tetanus-Pertussis Vaccine; D018073:Haemophilus Vaccines; D008458:Measles Vaccine; D022542:Measles-Mumps-Rubella Vaccine; D009108:Mumps Vaccine; D012411:Rubella Vaccine; D014612:Vaccines; D017778:Vaccines, Combined; C061963:HibTITER protein, Haemophilus influenzae