title: Comparative effectiveness of acellular versus whole-cell pertussis vaccines in teenagers.
abstract: BACKGROUND
  During the 1990s, the United States switched from combined diphtheria, tetanus toxoids, whole-cell pertussis (DTwP) vaccines to combined acellular pertussis (DTaP) vaccines because of safety concerns. After a 2010-2011 pertussis outbreak, we sought to evaluate whether disease risk in 10 to 17 year olds differed between those who previously received DTwP from those who received DTaP.
  
  
  METHODS
  A case-control study among individuals born from 1994 to 1999 who received 4 pertussis-containing vaccines during the first 2 years of life at Kaiser Permanente Northern California (KPNC). We separately compared pertussis polymerase chain reaction (PCR)-positive cases with PCR-negative and KPNC-matched controls. We assessed risk of pertussis relative to vaccine type in early childhood (4 DTwPs, mixed DTwP/DTaP, or 4 DTaPs) by using conditional logistic regression stratified for calendar time and adjusted for gender, race, medical clinic, and receipt of reduced antigen content acellular pertussis (Tdap) vaccine.
  
  
  RESULTS
  We compared 138 PCR-positive cases with 899 PCR-negative and 54 339 KPNC-matched controls. Teenagers who had received 4 DTwPs were much less likely to be pertussis PCR-positive than those who had received 4 DTaPs (odds ratio 5.63, 95% confidence interval 2.55-12.46) or mixed DTwP/DTaP vaccines (odds ratio 3.77, 95% confidence interval 1.57-9.07). Decreasing number of DTwP doses was significantly associated with increased pertussis risk (P < .0001).
  
  
  CONCLUSIONS
  Teenagers who received DTwP vaccines in childhood were more protected during a pertussis outbreak than were those who received DTaP vaccines.
authors.affiliation: Kaiser Permanente Vaccine Study Center, Oakland, CA 94612, USA. nicola.klein@kp.org
authors.forename: Nicola P
authors.initials: NP
authors.lastname: Klein
authors.forename: Joan
authors.initials: J
authors.lastname: Bartlett
authors.forename: Bruce
authors.initials: B
authors.lastname: Fireman
authors.forename: Ali
authors.initials: A
authors.lastname: Rowhani-Rahbar
authors.forename: Roger
authors.initials: R
authors.lastname: Baxter
mesh_terms: D000293:Adolescent; D002140:California / Q000453:epidemiology; D016022:Case-Control Studies; D002648:Child; D022681:Diphtheria-Tetanus-acellular Pertussis Vaccines / Q000008:administration & dosage*; D005260:Female; D006801:Humans; D016015:Logistic Models; D008297:Male; D010567:Pertussis Vaccine / Q000008:administration & dosage*; D016133:Polymerase Chain Reaction; D018570:Risk Assessment; D014481:United States / Q000453:epidemiology; D014917:Whooping Cough / Q000453:epidemiology / Q000517:prevention & control*
chemical_list: D022681:Diphtheria-Tetanus-acellular Pertussis Vaccines; D010567:Pertussis Vaccine
keywords: acellular pertussis vaccine; pertussis infection; teenagers; whole cell pertussis vaccine