The study protocol of the evaluation for the preventive efficacy of the HPV vaccine for persistent HPV16/18 infection in Japanese adult women: the HAKUOH study

BACKGROUND: In general, human papillomavirus (HPV) vaccines have demonstrated efficacy in young women worldwide, but there is limited evidence on the efficacy of the quadrivalent HPV6/11/16/18 vaccine in adult women and no evidence of its effectiveness in Japanese adult women in particular. This study aims to evaluate the efficacy of the quadrivalent HPV6/11/16/18 vaccine for persistent HPV16/18 infection in Japanese women aged 27–45 years. METHODS: This is an interventional, nonrandomized, non-double-blind prospective cohort study designed to compare the rates of persistent HPV16/18 infection between the vaccinated arm and unvaccinated arm. The subjects will consist of all women aged 27–45 years who have normal cytology results confirmed by cervical cancer screening from May 2019 to March 2021. The follow-up time is two years. The subjects will be divided into two groups: the vaccinated group and the unvaccinated group. The study will need to enroll 600 vaccinated participants (experimental arm) and 2200 unvaccinated participants (control arm). DISCUSSION: The findings of this trial (HAKUOH study) might provide the first local evidence on the subject and be significantly useful not only to medical academia but also to the Japanese Ministry of Health, Labour and Welfare. The findings could contribute to public health improvement by providing local supportive knowledge on the prevention of HPV infection through HPV vaccination in young adult women in Japan, where active recommendations have been suspended for a long time due to adverse effects. TRIAL REGISTRATION: Trial registration number: NCT04022148. Registration began on December 1, 2019.