Influence of nonavalent HPV vaccination after LEEP on follow-up findings: A single-center retrospective cohort study

INTRODUCTION: This study aimed to evaluate the effect of post-treatment administration of the nonavalent HPV vaccine on HPV clearance, cervical cytology outcomes, and HSIL recurrence during follow-up in women who underwent loop electrosurgical excision procedure (LEEP) for HSIL/(histological).
METHODS: This single-center retrospective cohort study included 200 women aged 18–65 years who underwent LEEP for histologically confirmed HSIL/CIN2–3 between 2020 and 2025 and had no prior HPV vaccination. Participants were grouped according to post-LEEP vaccination status: those who received the three-dose nonavalent HPV vaccine at 0, 2, and 6 months after LEEP (n=100) and unvaccinated controls (n=100). Co-testing was performed at 6 and 18 months, with colposcopy conducted as indicated per 2019 ASCCP guidelines.
RESULTS: There were no statistically meaningful differences between groups regarding HPV genotype distribution, or cytology findings. At 6 months, HPV negativity (70% vs. 77%; p = 0.262) and cytology negativity (73% vs. 76%; p = 0.626) rates were comparable between unvaccinated and vaccinated groups. At 18 months, the vaccinated group showed significantly higher HPV (91% vs. 81%; p = 0.042) and cytology negativity rates (93% vs. 81%; p = 0.012). HSIL rates were numerically lower in vaccinated patients at both follow-ups but did not reach statistical significance. Multivariate analysis showed HPV vaccination was independently associated with reduced 18-month HPV (OR = 0.42) and cytology positivity (OR = 0.32).
DISCUSSION AND CONCLUSION: Post-LEEP nonavalent HPV vaccination was not associated with early follow-up differences but was independently linked to improved mid-term HPV clearance and cytologic outcomes.

Keywords: High-grade squamous intraepithelial lesion (HSIL), Loop electrosurgical excision procedure (LEEP), Nonavalent HPV vaccine, HPV clearance.