Human papillomavirus vaccine effectiveness within a cervical cancer screening programme: cohort study

OBJECTIVE: To assess the effectiveness of an HPV vaccination programme in reducing the risk of cervical abnormalities identified at subsequent screening. DESIGN: Retrospective cohort study using administrative health data. SETTING: General population of Ferrara Province, Italy. POPULATION: Female residents born in 1986-1993 and participating in the organized cervical screening programme in 2011-2018, who were eligible for HPV vaccination in catch-up cohorts. METHODS: Logistic regression to evaluate the potential association between abnormal cervical cytology and one, two, three or at least one dose of HPV vaccine. MAIN OUTCOME MEASURES: Cervical abnormalities, as predicted by low-grade or high-grade cytology, by number of vaccine doses, stratified by age. RESULTS: The sample consisted of 7785 women (mean age 27.5 years, SD 2.3). Overall, 391 (5.0%) were vaccinated with ≥1 dose and 893 (11.5%) had abnormal cytology. Women receiving at least one vaccine dose were significantly less likely to have an abnormal cytology (adjusted odds ratio 0.52; 95% confidence interval 0.34-0.79). Similar results were observed for women receiving a single dose, for both bivalent and quadrivalent vaccines, and applying buffer periods (excluding cytological outcomes within 1 month, 6 months and 1 year of the first dose). CONCLUSIONS: In the context of an organised cervical screening programme in Italy, catch-up HPV vaccination almost halved the risk of cytological abnormalities. TWEETABLE ABSTRACT: Among Ferrara women, vaccination against human papillomavirus halved the risk of screening cervical abnormalities.