Reduction of HPV16/18 prevalence in young women after eight years of three- and two-dose vaccination schemes.

Abstract Background Recommendations for human papillomavirus vaccination have relied on immunogenicity studies and efficacy results derived from adult women. Insufficient information exists regarding HPV effectiveness in vaccinated girls as they become sexually active, regardless of dose scheme. We aimed to compare the prevalence of high-risk HPV between unvaccinated and vaccinated young women eight years after immunization. Methods After eight years, we recontacted women who received two-dose of bivalent or three-dose—either bivalent or quadrivalent—, HPV vaccine when aged 9–10 years-old as part of a clinical trial. Additionally, we recruited a contemporaneous unvaccinated woman group for comparison. Only those sexually active were included. High-risk HPV DNA was determined in urine samples and compared across groups. Results The prevalence of HPV16/18 types was 6.8% (95 %CI 3.2–14.1%) in the unvaccinated (n = 6/88), 1.1% (95 %CI 0.2–5.8%) in the three-dose (n = 1/93), and 0.0% (95 %CI 0.0–7.0%) in the two-dose group (n = 0/51). Conclusion HPV vaccination, with two-dose of bivalent or three-dose schemes—either with the bivalent or quadrivalent vaccine—, was associated with a lower prevalence of HPV16/18 types eight years after primary immunization.