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Women previously vaccinated against human papillomavirus (HPV) type 16 and 18 are now reaching the age (21 years) at which cervical-cancer screening is recommended in the U.S. The impact of HPV vaccination on risks of cervical precancer following a positive and negative screen among women aged 21-24 years who just started routine cervical screening are not well described. Therefore, three-year absolute and relative (RR) cumulative risks of cervical intraepithelial neoplasia grade 2 or more severe diagnoses (≥CIN2) and grade 3 or more severe diagnoses (≥CIN3) were estimated for women undergoing cervical screening at Kaiser Permanente Northern California. Risks were estimated in women aged 21-24 years (n = 75,008) undergoing cervical screening since late 2006, 6 months after HPV vaccination became available; women were categorized vaccinated at ages <18, 18-20, and 21-24 years and compared to those who were unvaccinated. Three-year risks were estimated for normal, low-grade, and high-grade cytology results. Three-year risks of ≥CIN2 and ≥CIN3 for unvaccinated women following low-grade cytology were 10.89% for and 3.70%, respectively. By comparison, Three-year risks of ≥CIN2 and ≥CIN3 were 5.26% (RR = 0.48, 95%CI = 0.24-0.99) and 0.99% (RR = 0.27, 95%CI = 0.06-1.13), respectively, for women vaccinated under the age of 18 years. Three-year ≥CIN2 and ≥CIN3 risks were lower for those HPV vaccinated at younger age for any screening result (ptrend ≤ 0.01 for all comparisons). These data support initiating cervical screening at an older age or changing the management of a low-grade cytology result in women aged 21-24 years who were vaccinated against HPV younger than age of 18 years. [ABSTRACT FROM AUTHOR]

In 2007, five Emerging Infections Program (EIP) sites were funded to determine the feasibility of establishing a population-based surveillance system for monitoring the effect of human papillomavirus (HPV) vaccine on pre-invasive cervical lesions. The project involved active population-based surveillance of cervical intraepithelial neoplasia grades 2 and 3 and adenocarcinoma in situ as well as associated HPV types in women >18 years of age residing in defined catchment areas; collecting relevant clinical information and detailed HPV vaccination histories for women 18-39 years of age; and estimating the annual rate of cervical cancer screening among the catchment area population. The first few years of the project provided key information, including data on HPV type distribution, before expected effect of vaccine introduction. The project's success exemplifies the flexibility of EIP's network to expand core activities to include emerging surveillance needs beyond acute infectious diseases. Project results contribute key information regarding the impact of HPV vaccination in the United States.