Alternative New Mono-scaled Quantitative Benefit–Risk Assessment of Human Papillomavirus Vaccine in Japan

Background: The human papillomavirus (HPV) vaccine coverage is very low in Japan since the government suspended the active encouragement of the vaccination. We aimed to conduct a benefit–risk assessment of HPV vaccination and explore different consequent scenarios to identify potential improvements to the current Japanese immunization program. Methods: To calculate social benefit–risk of HPV vaccine, we used the Markov model to represent the natural history of HPV and adverse events (AEs) using disability-adjusted life year (DALY) as the outcome. Benefits and risks were calculated as the sum of negative and positive outcomes corresponding to all preventable diseases and AEs associated with HPV vaccination, respectively. The benefit–risk balance in 2050 was estimated using published data. Results: Our model was confirmed by published cervical cancer incidence and mortality rates. The benefit–risk balance in 2050 showed that the most effective scenario was the introduction of 9-valent HPV vaccine targeting female individuals aged 10–29 years for routine vaccination starting in 2020, although there is possibility of increased risks of AEs for the vaccinated age group post resumption of recommendations. Conclusion: Our benefit–risk assessment of HPV vaccine helped estimate various scenarios pertaining to HPV vaccination and identify the best strategy regarding HPV vaccination. This benefit–risk assessment approach may be used for other vaccines and vaccination programs.