title: Estimating the effectiveness of tetanus-diphtheria-acellular pertussis vaccine (Tdap) for preventing pertussis: evidence of rapidly waning immunity and difference in effectiveness by Tdap brand.
abstract: BACKGROUND
  We estimated the vaccine effectiveness (VE) of tetanus-diphtheria-acellular pertussis vaccine (Tdap) for preventing pertussis among adolescents during a statewide outbreak of pertussis in Wisconsin during 2012.
  
  
  METHODS
  We used the population-based Wisconsin Immunization Registry (WIR) to construct a cohort of Wisconsin residents born during 1998-2000 and collect Tdap vaccination histories. Reports of laboratory-confirmed pertussis with onset during 2012 were matched to WIR clients. Incidence rate ratios (IRRs) of pertussis and Tdap VE estimates [(1 - IRR)*100%], by year of Tdap vaccine receipt and brand (Boostrix/Adacel), were estimated using Poisson regression.
  
  
  RESULTS
  Tdap VE decreased with increasing time since receipt, with VEs of 75.3% (95% confidence interval [CI], 55.2%-86.5%) for receipt during 2012, 68.2% (95% CI, 60.9%-74.1%) for receipt during 2011, 34.5% (95% CI, 19.9%-46.4%) for receipt during 2010, and 11.9% (95% CI, -11.1% to 30.1%) for receipt during 2009/2008; point estimates were higher among Boostrix recipients than among Adacel recipients. Among Tdap recipients, increasing time since receipt was associated with increased risk, and receipt of Boostrix (vs Adacel) was associated with decreased risk of pertussis (adjusted IRR, 0.62 [95% CI, .52-.74]).
  
  
  CONCLUSIONS
  Our results demonstrate waning immunity following vaccination with either Tdap brand. Boostrix was more effective than Adacel in preventing pertussis in our cohort, but these findings may not be generalizable to adolescent cohorts that received different diphtheria-tetanus-acellular pertussis vaccines (DTaP) during childhood and should be further examined in studies that include childhood DTaP history.
authors.affiliation: Bureau of Communicable Diseases and Emergency Response, Wisconsin Division of Public Health Department of Pediatrics.
authors.forename: Ruth
authors.initials: R
authors.lastname: Koepke
authors.affiliation: Department of Biostatistics and Medical Informatics, School of Medicine and Public Health, University of Wisconsin-Madison, Madison.
authors.forename: Jens C
authors.initials: JC
authors.lastname: Eickhoff
authors.affiliation: Bureau of Communicable Diseases and Emergency Response, Wisconsin Division of Public Health Department of Pediatrics.
authors.forename: Roman A
authors.initials: RA
authors.lastname: Ayele
authors.affiliation: Bureau of Communicable Diseases and Emergency Response, Wisconsin Division of Public Health Department of Pediatrics.
authors.forename: Ashley B
authors.initials: AB
authors.lastname: Petit
authors.affiliation: Bureau of Communicable Diseases and Emergency Response, Wisconsin Division of Public Health.
authors.forename: Stephanie L
authors.initials: SL
authors.lastname: Schauer
authors.affiliation: Bureau of Communicable Diseases and Emergency Response, Wisconsin Division of Public Health.
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: Hopfensperger
authors.affiliation: Department of Pediatrics.
authors.forename: James H
authors.initials: JH
authors.lastname: Conway
authors.affiliation: Bureau of Communicable Diseases and Emergency Response, Wisconsin Division of Public Health.
authors.forename: Jeffrey P
authors.initials: JP
authors.lastname: Davis
mesh_terms: D000293:Adolescent; D015721:Diphtheria-Tetanus-Pertussis Vaccine / Q000276:immunology / Q000627:therapeutic use; D022681:Diphtheria-Tetanus-acellular Pertussis Vaccines / Q000276:immunology / Q000627:therapeutic use*; D004196:Disease Outbreaks / Q000517:prevention & control; D006801:Humans; D015994:Incidence; D012042:Registries; D016896:Treatment Outcome; D014917:Whooping Cough / Q000453:epidemiology / Q000276:immunology / Q000517:prevention & control*; D014922:Wisconsin / Q000453:epidemiology
chemical_list: C505143:Boostrix; D015721:Diphtheria-Tetanus-Pertussis Vaccine; D022681:Diphtheria-Tetanus-acellular Pertussis Vaccines; C509326:adacel
keywords: Bordetella pertussis; Tdap (tetanus-diphtheria-acellular pertussis) vaccine; epidemiology; immunization information systems; vaccine effectiveness