HPV and Cytology Testing in Women Undergoing 9-Valent HPV Opportunistic Vaccination: A Single-Cohort Follow Up Study.

Background: This study evaluates the possible effect of 9-valent (9vHPV) vaccination on the results of HPV and cytological tests in a cohort of adult women. Methods: This study is a retrospective, single-cohort, monocentric study. Sexually active women aged 14-70 years, who underwent 9vHPV vaccination, were enrolled. Dose administration dates, side effects and data on Pap smears and HPV tests performed before and after the first vaccine dose were collected. Subjects were considered "unexposed" to the vaccine for all time intervals before the first dose administration, and "exposed" to the first, second and third vaccine doses in all time intervals following each specific dose. Results: A total of 512 women underwent the first 9vHPV dose administration and were enrolled in the study. Median age at vaccination was 30.5 (14-70). Log-rank tests and Cox regression analyses showed a highly statistically significant (p < 0.0001) difference in the time to negativization after the exposure to the third vaccine dose in the 207 women starting with a Pap+ smear (HR (95% C.I.), 2.66 (1.83-3.86)) and in the 198 women starting with an HPV HR+ test (HR (95% C.I.), 7.80 (4.83-12.60)). Conclusions: 9vHPV vaccination may play a role in shortening the clearance time of HPV HR+ or Pap positivity in sexually active adult women.