title: Reduced risk of pertussis among persons ever vaccinated with whole cell pertussis vaccine compared to recipients of acellular pertussis vaccines in a large US cohort.
abstract: BACKGROUND
  Unexpected waning of immunity after pertussis vaccination is now well described. In this study we examined whether prior vaccination with whole-cell pertussis vaccine (wP) at any point provided superior protection contrasted with a solely acellular pertussis vaccine (aP) series. We utilized the coincidence of a large outbreak of pertussis with the termination of wP availability, providing populations of children who had been vaccinated with combinations of wP and aP.
  
  
  METHODS
  Kaiser Permanente (KP) is an integrated healthcare system with complete electronic records and a centralized laboratory. Cases of laboratory-confirmed pertussis and vaccination data for members aged 8-20 years were retrieved.
  
  
  RESULTS
  Among 263 496 persons aged 8-20 years, 904 cases of pertussis were identified. In patients with a full history of vaccinations administered by KP, those with 5 total doses of only aP had an 8.57 relative risk (RR) of pertussis (P < .0001) contrasted to those with ≥1 wP dose. With 6 doses of aP, the RR of disease was 3.55 (P < .0001). When external vaccine records were included, the results were similar.
  
  
  CONCLUSIONS
  We found a markedly increased risk of disease associated with an entirely aP series. This risk was mitigated, but not eliminated, by the presence of a sixth dose of pertussis vaccine (Tdap). Receipt of 1 or more wP doses markedly augmented the durability of immunity from subsequent aP doses. It appears that a wholly acellular pertussis vaccine series is significantly less effective and durable than one that contains the traditional whole cell vaccine.
authors.affiliation: Department of Infectious Diseases, Kaiser Permanente Medical Center, 99 Montecillo Rd, San Rafael, CA 94903, USA.
authors.forename: Maxwell A
authors.initials: MA
authors.lastname: Witt
authors.forename: Larry
authors.initials: L
authors.lastname: Arias
authors.forename: Paul H
authors.initials: PH
authors.lastname: Katz
authors.forename: Elizabeth T
authors.initials: ET
authors.lastname: Truong
authors.forename: David J
authors.initials: DJ
authors.lastname: Witt
mesh_terms: D000293:Adolescent; D002648:Child; D004196:Disease Outbreaks; D005260:Female; D006801:Humans; D008297:Male; D008329:Managed Care Programs; D010567:Pertussis Vaccine / Q000008:administration & dosage* / Q000276:immunology*; D015995:Prevalence; D012307:Risk Factors; D014481:United States / Q000453:epidemiology; D022282:Vaccines, Acellular / Q000008:administration & dosage / Q000276:immunology; D014917:Whooping Cough / Q000453:epidemiology* / Q000276:immunology / Q000517:prevention & control*; D055815:Young Adult
chemical_list: D010567:Pertussis Vaccine; D022282:Vaccines, Acellular