title: Post-marketing safety evaluation of a tetanus toxoid, reduced diphtheria toxoid and 3-component acellular pertussis vaccine administered to a cohort of adolescents in a United States health maintenance organization.
abstract: BACKGROUND
  Prelicensure clinical studies may not include sufficient numbers of subjects to assess the potential for rare postvaccination adverse events. The aim of this postlicensure study (NCT00297856) was to evaluate uncommon outcomes following vaccination with a tetanus, reduced-antigen-content diphtheria, and acellular pertussis vaccine (Tdap, Boostrix GlaxoSmithKline) in a large adolescent cohort.
  
  
  METHODS
  We monitored safety outcomes among 13,427 10 to 18-year-old adolescents enrolled in the Northern California Kaiser Permanente Health Care Plan who received Tdap vaccination as part of their normal health care. Subjects were evaluated using self-control analysis comparing days 0 to 29 to days 30 to 59 postvaccination for neurologic events, hematologic events and allergic reactions. We evaluated new onset chronic illnesses within 6 months of Tdap vaccination by comparing with historical Td controls matched for age at vaccination, season, sex, and geographic area. We also compared the incidence of events of interest between the Tdap and historical cohorts as exploratory analyses.
  
  
  RESULTS
  No increased risk for medically attended neurologic (odds ratio [OR], 0.962; 95% confidence interval [CI], 0.533-1.733) or allergic reactions (OR, 1.091; 95% CI, 0.441-2.729) was observed following Tdap vaccination when comparing the first 30 postvaccination days to the second 30 postvaccination days. There was one hematologic event within 30 days of Tdap, compared with 0 events within days 30 to 59 (P = 1.0). When compared with matched historical Td recipients, no increase in new onset chronic illnesses (OR, 0.634; 95% CI, 0.475-0.840) was seen after Tdap. No deaths occurred in the Tdap cohort during the study.
  
  
  CONCLUSIONS
  This study provides no evidence for an increased risk for neurologic, hematologic, allergic events, or new onset of chronic illnesses among adolescents vaccinated with Tdap.
authors.affiliation: Kaiser Permanente Vaccine Study Center, Oakland, CA, USA. nicola.klein@kp.org
authors.forename: Nicola P
authors.initials: NP
authors.lastname: Klein
authors.forename: John
authors.initials: J
authors.lastname: Hansen
authors.forename: Edwin
authors.initials: E
authors.lastname: Lewis
authors.forename: Liisa
authors.initials: L
authors.lastname: Lyon
authors.forename: Bessie
authors.initials: B
authors.lastname: Nguyen
authors.forename: Steven
authors.initials: S
authors.lastname: Black
authors.forename: Wayde M
authors.initials: WM
authors.lastname: Weston
authors.forename: Sterling
authors.initials: S
authors.lastname: Wu
authors.forename: Ping
authors.initials: P
authors.lastname: Li
authors.forename: Barbara
authors.initials: B
authors.lastname: Howe
authors.forename: Leonard R
authors.initials: LR
authors.lastname: Friedland
mesh_terms: D000293:Adolescent; D002140:California; D002648:Child; D015721:Diphtheria-Tetanus-Pertussis Vaccine / Q000009:adverse effects*; D006279:Health Maintenance Organizations; D006402:Hematologic Diseases / Q000139:chemically induced; D006801:Humans; D006967:Hypersensitivity; D015994:Incidence; D008297:Male; D009422:Nervous System Diseases / Q000139:chemically induced; D011358:Product Surveillance, Postmarketing
chemical_list: C505143:Boostrix; D015721:Diphtheria-Tetanus-Pertussis Vaccine