title: Effectiveness of quadrivalent human papillomavirus vaccine for the prevention of cervical abnormalities: case-control study nested within a population based screening programme in Australia.
abstract: OBJECTIVE
  To measure the effectiveness of the quadrivalent human papillomavirus (HPV) vaccine against cervical abnormalities four years after implementation of a nationally funded vaccination programme in Queensland, Australia.
  
  
  METHODS
  Case-control analysis of linked administrative health datasets.
  
  
  METHODS
  Queensland, Australia.
  
  
  METHODS
  Women eligible for free vaccination (aged 12-26 years in 2007) and attending for their first cervical smear test between April 2007 and March 2011. High grade cases were women with histologically confirmed high grade cervical abnormalities (n = 1062) and "other cases" were women with any other abnormality at cytology or histology (n = 10,887). Controls were women with normal cytology (n = 96,404).
  
  
  METHODS
  Exposure odds ratio (ratio of odds of antecedent vaccination (one, two, or three vaccine doses compared with no doses) among cases compared with controls), vaccine effectiveness ((1-adjusted odds ratio) × 100), and number needed to vaccinate to prevent one cervical abnormality at first screening round. We stratified by four age groups adjusted for follow-up time, year of birth, and measures of socioeconomic status and remoteness. The primary analysis concerned women whose first ever smear test defined their status as a case or a control.
  
  
  RESULTS
  The adjusted odds ratio for exposure to three doses of HPV vaccine compared with no vaccine was 0.54 (95% confidence interval 0.43 to 0.67) for high grade cases and 0.66 (0.62 to 0.70) for other cases compared with controls with normal cytology, equating to vaccine effectiveness of 46% and 34%, respectively. The adjusted numbers needed to vaccinate were 125 (95% confidence interval 97 to 174) and 22 (19 to 25), respectively. The adjusted exposure odds ratios for two vaccine doses were 0.79 (95% confidence interval 0.64 to 0.98) for high grade cases and 0.79 (0.74 to 0.85) for other cases, equating to vaccine effectiveness of 21%.
  
  
  CONCLUSIONS
  The quadrivalent HPV vaccine conferred statistically significant protection against cervical abnormalities in young women who had not started screening before the implementation of the vaccination programme in Queensland, Australia.
authors.affiliation: The University of Queensland, School of Population Health, Brisbane, Australia.
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Crowe
authors.forename: Nirmala
authors.initials: N
authors.lastname: Pandeya
authors.forename: Julia M L
authors.initials: JM
authors.lastname: Brotherton
authors.forename: Annette J
authors.initials: AJ
authors.lastname: Dobson
authors.forename: Stephen
authors.initials: S
authors.lastname: Kisely
authors.forename: Stephen B
authors.initials: SB
authors.lastname: Lambert
authors.forename: David C
authors.initials: DC
authors.lastname: Whiteman
mesh_terms: D000293:Adolescent; D000328:Adult; D016022:Case-Control Studies; D002584:Cervix Uteri / Q000473:pathology; D002648:Child; D005260:Female; D000068857:Human Papillomavirus Recombinant Vaccine Quadrivalent, Types 6, 11, 16, 18; D006801:Humans; D008403:Mass Screening / Q000706:statistics & numerical data*; D032541:Mass Vaccination / Q000706:statistics & numerical data; D053918:Papillomavirus Vaccines / Q000627:therapeutic use*; D011793:Queensland / Q000453:epidemiology; D016896:Treatment Outcome; D002577:Uterine Cervical Diseases / Q000453:epidemiology / Q000473:pathology / Q000517:prevention & control*; D014626:Vaginal Smears / Q000706:statistics & numerical data; D055815:Young Adult
chemical_list: D000068857:Human Papillomavirus Recombinant Vaccine Quadrivalent, Types 6, 11, 16, 18; D053918:Papillomavirus Vaccines