The Potential Impact of a Single-Dose HPV Vaccination Schedule on Cervical Cancer Outcomes in Kenya: A Mathematical Modelling and Health Economic Analysis.

Background: Human Papillomavirus (HPV) is the primary cause of cervical cancer. Single-dose HPV vaccination can effectively prevent high-risk HPV infection that causes cervical cancer and accelerate progress toward achieving cervical cancer elimination goals. We modelled the potential impact of adopting single-dose HPV vaccination strategies on health and economic outcomes in Kenya, where a two-dose schedule is the current standard. Methods: Using a validated compartmental transmission model of HPV and HIV in Kenya, we evaluated the costs from the payer's perspective to vaccinate girls by age 10 with either one or two doses and increasing coverage levels (0%, 70%, 77%, 90%). Additionally, we modelled single-dose strategies supplemented with either catch-up vaccination of adolescent girls and young women or vaccination for all by age 10, funded with the first five-years of cost savings of switching from a two- to one-dose schedule. Costs and outcomes were discounted at 3% annually, and incremental cost-effectiveness ratios (ICERs) were calculated per disability-adjusted-life-year (DALY) averted. Results: All one-dose and the two-dose 90% coverage strategies were on the efficiency frontier, dominating the remaining two-dose strategies. The two-dose 90% coverage strategy had a substantially higher ICER (US$6508.80/DALY averted) than the one-dose 90% coverage (US$197.44/DALY averted). Transitioning from a two- to one-dose schedule could result in US$21.4 Million saved over the first five years, which could potentially fund 2.75 million supplemental HPV vaccinations. With this re-investment, all two-dose HPV vaccination scenarios would be dominated. The greatest DALYs were averted with the single-dose HPV vaccination schedule at 90% coverage supplemented with catch-up for 11-24-year-old girls, which had an ICER of US$78.73/DALYs averted. Conclusions: Considering the logistical and cost burdens of a two-dose schedule, a one-dose schedule for girls by age 10 would generate savings that could be leveraged for catch-up vaccination for older girls and accelerate cervical cancer elimination in Kenya.