HPV Vaccination and HPV Outcomes After LEEP: A Retrospective Population-Based Cohort Study from Northern Norway,...

Background/Objectives: Women treated with loop electrosurgical excision procedure (LEEP) for high-grade cervical intraepithelial neoplasia (CIN2+) remain at risk of HPV detection during follow-up. We assessed whether HPV vaccination was associated with HPV positivity at the first post-treatment follow-up after LEEP. Methods: This retrospective population-based cohort included women aged 20-79 years treated by LEEP in Troms and Finnmark, Norway, during 2022-2024 (n = 1052). Vaccination status, timing, and vaccine product were obtained from the national immunization register (SYSVAK). Follow-up HPV results (overall HPV, HPV16, HPV18, and pooled other HPV types; Roche cobas 4800 channels) were retrieved from SymPathy. Results: Overall, 329/1052 women (31.3%) were HPV-positive at first follow-up. HPV positivity was 37.7% (200/530) among unvaccinated women and 24.7% (129/522) among vaccinated women (ARR 13.0 percentage points; 95% CI 7.5-18.6; RR 0.655; 95% CI 0.544-0.788; p = 5.2 × 10^-6). HPV16 was detected in 5.9% vs. 9.4% (p = 0.0335), and pooled other HPV types in 18.0% vs. 28.7% (p = 4.3 × 10^-5); HPV18 did not differ (2.9% vs. 2.5%; p = 0.671). In adjusted analyses, vaccination in the year of LEEP was associated with lower risk of follow-up HPV positivity (aRR 0.592; 95% CI 0.444-0.789; p = 0.000348). Conclusions: HPV vaccination before the first post-treatment follow-up was associated with lower HPV positivity after LEEP. As this outcome is a surrogate endpoint and residual confounding is possible, studies with standardized follow-up and long-term clinical endpoints are needed.