A Retrospective Cohort Study of Young Women Spontaneously Choosing to Be Vaccinated against HPV: Outcomes from Their First Cervical Cancer Screening Test

Abstract

Background: Efficacy for cervical cancer prevention of opportunistic HPV vaccination in post-pubertal girls is lower than in 11-year-olds. Methods: Women born between 1986 and 1992 vaccinated at 15–25 years of age (at least one dose of 4-valent HPV vaccine) and screened at 24–27 years of age were included. Frequency of opportunistic vaccination, overall and by birth cohort, was calculated; screening outcomes were compared between vaccinated and unvaccinated women. Results: Overall, 4718 (4.9%) HPV-vaccinated, and 91,512 unvaccinated, women were studied. The frequency of vaccination increased by birth cohort, ranging between 1.8% and 9.8%; age at vaccination decreased progressively by birth cohort (p < 0.0001). Participation in screening was 60.8% among vaccinated, and 56.6% among unvaccinated, women (p < 0.0001). Detection rates (DR) for high-grade lesions were lower in vaccinated women (2.11‰ vs. 3.85‰ in unvaccinated, for CIN3+, p = 0.24; 0.0‰ vs. 0.22‰ for cancer). The DR of CIN3+ increased with age at vaccination, scoring respectively 0.0‰, 0.83‰, and 4.68‰ for women vaccinated when they were 15–16, 17–20, and 21–25 years old (p = 0.17). Conclusions: In comparison to unvaccinated women, higher compliance with cervical cancer screening invitation and lower CIN3+ DR among vaccinated women was observed. Age at vaccination was inversely correlated to vaccination efficacy.

Impact of a Human Papillomavirus Vaccination Program within Organized Cervical Cancer Screening: Cohort Study

“…Since 2001, the organized cervical screening programme offers (conventional) Pap smear testing every three years to 25-64-year old women. 10 Colposcopy is the second level diagnostic test for women with positive Pap smears (atypical squamous cells of undetermined significance or worse -ASC-US+), and the threshold for treatment is generally Cervical Intraepithelial Neoplasia grade 2 (CIN2), although, depending on the clinical situation, women with CIN1 may also be treated. 11 The HPV voluntary vaccination programme started in 2008, offering three doses of the bivalent vaccine to 11-12-year old females for free, 12 while catch-up vaccination for older women required copayment.…”

“…While type-specific HPV prevalence and abnormal cytology and histology in vaccinated populations were previously investigated in Italy, 9,10,22 this is the first evaluation of vaccine herd protection in the country. Other strengths of the study are the relatively high screening uptake, 14,23 and the use of deterministic linkage of vaccination and screening registries, which minimizes the possibility of reporting, selection, and misclassification bias.…”

The Consensus Project: Participation in cervical cancer screening by the first cohorts of girls offered HPV vaccination at age 15–16 years in Italy

“…10 The project has involved 5 regions: 3 of them (Piedmont, Liguria and Tuscany) have introduced a multi-cohort vaccination programme that includes 15–16-year-old girls, and 2 of them (Emilia-Romagna and Veneto) have only implemented opportunistic vaccination for these birth cohorts. 11 Supplemental File S1 reports the project goals and protocol of the Consensus Intervention Study.…”

“…1 In 2008, 5 regions (Valle d'Aosta, Piedmont, Friuli-Venezia Giulia, Basilicata and Tuscany) initiated free, multi-cohort, HPV vaccination campaigns targeting also 15-16-year-old girls (born in 1993, 1994 and 1995). 2 The first available vaccines were the bivalent (HPV 16,18) and the quadrivalent (HPV 6,11,16,18). 3 In 2017, the nonavalent vaccine (HPV 6,11,16,18,31,33,45,52,58) became available in Italy to both sexes.…”

“…2 The first available vaccines were the bivalent (HPV 16,18) and the quadrivalent (HPV 6,11,16,18). 3 In 2017, the nonavalent vaccine (HPV 6,11,16,18,31,33,45,52,58) became available in Italy to both sexes. 4 The introduction of HPV vaccination programmes has had a substantial impact on the incidence of HPV infections and preneoplastic lesions of the cervix in almost all countries in which it has been assessed.…”