Declines in Human Papillomavirus (HPV)-Associated High-Grade Cervical Lesions After Introduction of HPV Vaccines in Connecticut, United States, 2008-2015

Clin Infect Dis. 2017 Sep 15;65(6):884-889. doi: 10.1093/cid/cix455.


Background: Trends in human papillomavirus (HPV)-associated cervical lesions can provide an indication of vaccine impact. Our purpose was to measure trends in cervical lesions during 2008-2015 and to consider possible explanations including vaccination coverage, changes in screening for cervical cancer, and risk behaviors for acquiring HPV.

Methods: Connecticut (CT) implemented mandatory reporting of cervical intraepithelial neoplasia grades 2/3 and adenocarcinoma in situ (cervical intraepithelial neoplasia grade 2 or higher [CIN2+]) in 2008. Trends by age and birth cohort were modeled using negative binomial regression and change-point methods. To evaluate possible explanations for changes, these trends were compared to changes in HPV vaccination coverage, cervical cancer screening, an antecedent event to detection of a high-grade lesion, and changes in sexual behaviors and Chlamydia trachomatis, an infection with similar epidemiology to and shared risk factors for HPV.

Results: A significant decline in CIN2+ was first evident among women aged 21 years in 2010, followed by successive declines in women aged 22-26 years during 2011-2012. During 2008-2015, the rates of CIN2+ declined by 30%-74% among women aged 21-26 years, with greater declines observed in the younger women. Birth cohorts between 1985 and 1994 all experienced significant declines during the surveillance period, ranging from 25% to 82%. Ecological comparisons revealed substantial increases in HPV vaccination during this time period, and more modest reductions in cervical cancer screening and sexual risk behaviors.

Conclusions: The age and cohort patterns in our data suggest that declines in CIN2+ during 2008-2015 are more likely driven by HPV vaccination, introduced in 2006, than by changes in screening or risk behavior.

Keywords: cervical lesions; human papillomavirus; surveillance; vaccination; vaccine impact.

MeSH terms

  • Adenocarcinoma in Situ / epidemiology*
  • Adenocarcinoma in Situ / prevention & control
  • Adenocarcinoma in Situ / virology
  • Adult
  • Chlamydia Infections / epidemiology*
  • Chlamydia trachomatis*
  • Connecticut / epidemiology
  • Early Detection of Cancer / trends
  • Female
  • Humans
  • Incidence
  • Papillomavirus Vaccines*
  • Unsafe Sex / statistics & numerical data
  • 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
  • Vaccination Coverage / trends
  • Young Adult


  • Papillomavirus Vaccines