Assessing the Health and Economic Outcomes of a 9-Valent HPV Vaccination Program in the United Kingdom.

Background: The United Kingdom (UK) switched from using the 4-valent human papillomavirus (HPV) vaccine (Gardasil®) to the 9-valent vaccine (Gardasil 9®) in 2021. Objective: To estimate and compare the health and economic outcomes of 2 HPV vaccination programs in the UK targeting girls and boys aged 12-13 years from the perspective of the UK National Health Service. The 2 vaccination strategies were (1) universal vaccination 4-valent (UV4V), using the 4-valent HPV vaccine (4vHPV), and (2) universal vaccination 9-valent (UV9V), using the 9-valent HPV vaccine (9vHPV). Methods: A deterministic heterosexual compartmental disease transmission model was used to track health and economic outcomes over a 100-year time horizon. Outcomes were discounted at an annual rate of 3.5% and 1.5%. All costs were adjusted to 2020 British pounds (£). Health outcomes were measured in quality-adjusted life-years (QALYs), and the summary results were presented as incremental cost-effectiveness ratios (£/QALY gained) when comparing UV4V with UV9V. Results: Using the same vaccine coverage for both programs, the total cumulative cases of HPV-related health outcomes tracked over the 100-year horizon indicated that the relative number of cases averted (UV9V vs UV4V) ranged from 4% (anal male cancers and deaths) to 56% (cervical intraepithelial neoplasia [CIN1]). Assuming that 9vHPV cost £15.18 more than 4vHPV (a cost differential based on discounted list prices), the estimated incremental cost-effectiveness ratio was £8600/QALY gained when discounted at 3.5%, and £3300/QALY gained when discounted at 1.5%. The estimated incremental cost-effectiveness ratios from the sensitivity analyses remained <£28000/QALY over a wide range of parameter inputs and demonstrated that disease utilities, discount rate, and vaccine efficacy were the 3 most influential parameters. Discussion: Consistent with other published studies, the results from this study found that the 9vHPV vaccine prevented a substantial number of cases when compared with the 4vHPV vaccine and was highly cost-effective. Conclusions: These results demonstrate that replacing universal 4vHPV with 9vHPV can prevent a substantial additional number of HPV-related cases/deaths (in both women and men) and remain cost-effective over a range of 9vHPV price premiums.