Reduction in cervical intraepithelial neoplasia in young women in British Columbia after introduction of the HPV vaccine: An ecological analysis

Int J Cancer. 2015 Oct 15;137(8):1931-7. doi: 10.1002/ijc.29508. Epub 2015 Jun 3.


We report on the rates of cervical intraepithelial neoplasia (CIN) in young women aged 15-22 years of age in British Columbia before and after the introduction of an HPV vaccine program. Rates of cervical intraepithelial neoplasia (CIN) 2+ for each age stratum (15-22) in the calendar years 2004-2012 for the province of British Columbia were obtained from the BC Cancer Agency's population-based cervical cancer program. Incidence rate ratios (IRR) of CIN2+ were described and compared before and after HPV vaccine program introduction in cohorts born in vaccine eligible years, and in non-vaccine eligible years using piece-wise Poisson regression analysis, and adjusted for age. Between 2004 and 2012, rates of CIN2 and CIN2+ in young women aged 15-22 years in the province of British Columbia have decreased overall. After the introduction of the HPV vaccine program, the age adjusted IRR for CIN2+ for young women aged 15-17 years decreased significantly from 0.91 (95% CI: 0.86-0.98 p < 0.01) to 0.36 (95% CI: 0.18-0.73 p < 0.01). During the same time period, no similar reduction was found in young women 18-22 years. After introduction of HPV vaccine program, IRR for CIN2+ in young women 15-17 was significantly reduced for CIN2+ (0.14; 95% CI: 0.04- 0.47; p < 0.01) and CIN2 (0.1; 95% CI: 0.02-0.54; p < 0.01). This ecological analysis shows a significant reduction in CIN2+ lesions in young women aged 15-17 years in British Columbia after the introduction of the HPV vaccine in young women despite vaccine uptake levels below 70%.

Keywords: HPV vaccine; cervical intraepithelial neoplasia; human papillomavirus; primary cancer prevention; vaccination program.

MeSH terms

  • Adolescent
  • Adult
  • British Columbia / epidemiology
  • Female
  • Humans
  • Papillomavirus Infections / prevention & control*
  • Papillomavirus Vaccines / therapeutic use*
  • Regression Analysis
  • Uterine Cervical Dysplasia / epidemiology*
  • Uterine Cervical Dysplasia / prevention & control
  • Uterine Cervical Dysplasia / virology
  • Uterine Cervical Neoplasms / epidemiology*
  • Uterine Cervical Neoplasms / prevention & control
  • Uterine Cervical Neoplasms / virology
  • Young Adult


  • Papillomavirus Vaccines