Introduction Human papillomavirus (HPV) vaccine, which provides protection against oncogenic HPV types 16 and 18, was licensed in the United States (US) in late 2006. HPV 16 and 18 are associated with approximately 25% of low-grade and 50% of high-grade cervical intraepithelial lesions worldwide. HPV vaccination is recommended for US girls aged 11–12 years, with catch-up vaccination through age 26; in 2013 coverage among girls aged 13–17 was 57% for 1 dose and 38% for 3 doses.
Methods Using health care claims data from 9.7 million privately insured females aged 10–39 years, we estimated the annual prevalence of cytologically-detected cervical low-grade and high-grade squamous intraepithelial lesions (LSIL and HSIL, respectively), and of histologically-detected cervical intraepithelial neoplasia grades 2 and 3 (high-grade lesions, collectively termed CIN2+), during 2007–2013. To account for changes in cervical cancer screening over time, analyses were restricted to females who were screened during the same calendar year. Age-stratified trend tests were conducted using binomial regression.
Results Prevalence of LSIL, HSIL and CIN2+ decreased significantly during 2007–2013 for females aged 10–14 and 15–19. For those aged 15–19, prevalence of LSIL decreased by 50% (53.2 to 26.8 per 1000 person-years, P < 0.001) and HSIL decreased by 72% (5.9 to 1.6, P < 0.001); CIN2+ prevalence in this age group decreased by 83% (13.4 to 2.3, P < 0.001). Prevalence of HSIL and CIN2+ also decreased significantly for women aged 20–24. No decreases were seen in older women.
Conclusion This is the first US study to find decreased prevalence of cervical lesions in the age groups most likely to be impacted by HPV vaccination, while accounting for changes in cervical cancer screening. Decreases in low-grade and high-grade lesions reflected their relative associations with HPV types 16 and 18. These results provide ecologic evidence of population effectiveness of HPV vaccination among young, privately-insured US women.
Disclosure of interest statement This work was funded by the Centres for Disease Control and Prevention.
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