Impact of Human papillomavirus 9-valent vaccine on viral clearance after surgical treatment: A single-center retrospective observational study

Introduction: The effectiveness of post-treatment HPV vaccination with the Human papillomavirus 9-valent (9vHPV) vaccine in women treated with loop electrosurgical excision procedure (LEEP) for high-grade cervical intraepithelial neoplasia (CIN2-3) or laser ablation (LA) for low-grade lesions (CIN1) remains a topic of ongoing research. Study design: This single-center retrospective observational study included 326 women aged 25 to 65 years who underwent surgical treatment between 2020 and 2024. Participants were divided into two groups: vaccinated (V) and non-vaccinated (NV). A further stratification was then reported by age < 40 years (n = 174) and >= 40 years (n = 152). The primary outcomes were HPV test results and colposcopy findings 6-15 months post-treatment, evaluating the potential adjuvant effect of HPV vaccination. Results: The vaccinated group (V-group) comprised 68 % (222/326) of participants, while 32 % (104/326) were unvaccinated (NV-group). Among women treated for CIN1, a positive HPV test was detected in 38 % of unvaccinated women compared to 18 % in vaccinated women (p = 0.0169). Among those treated for CIN2-3, 18 % of unvaccinated women had a positive HPV test, compared to 8 % in the vaccinated group (p = 0.0353). Vaccination, also in women with an age >= 40-year-old had a statistically significant effect in reducing the proportion of women with a positive HPV test (p = 0.0100). Conclusion: Human papillomavirus 9-valent vaccine was associated with a significant reduction in the proportion of women with a positive HPV test. These findings support its potential role in tertiary prevention of HPV-related cervical disease, particularly in reducing HPV persistence after surgical treatment.