A case-control study on cervical cancer screening outcome and HPV vaccination among young women in the Italian area of Udine

The age for starting cervical cancer screening for women who were fully vaccinated against human papilloma virus (HPV) in adolescence could be increased from 25 to 30 years. In Italy, some regional governments have revised their screening programs accordingly, though others haven't. Local data on the effectiveness of the HPV vaccine may be helpful in encouraging updates in the screening protocols. We conducted a case-control study based on routine-collected anonymized administrative health data to evaluate the outcomes of first round cervical screening in women living in the Udine area of Italy, according to their vaccinal status. In the study, we included women born between 1993 and 1997, those that were living in the Udine area from 2008 to 2022, and those that participated in the regional cervical cancer screening program for at least one round from 2018 to 2022 (n = 2191). Of these women, 850 had been fully vaccinated before 15 years of age, 887 were vaccinated at age 15 or later, 39 were incompletely vaccinated, and 415 had never been vaccinated. 2140 women had a negative pap-test result and 51 had some type of non-normal result. The odds ratio for having a non-negative result was 0.23 for vaccinated vs non-vaccinated women (95% confidence interval 0.13–0.40). Only 0.2% of vaccinated women had CIN2+ lesions compared to 1.0% of CIN2 and 2.6% of CIN3 of non-vaccinated women (odds ratio of CIN2+ was 0.10, 95% confidence interval 0.04–0.26). The first invitation to the regional cervical cancer screening could be delayed in women who were vaccinated against HPV.