The merits of sustaining pneumococcal vaccination after transitioning from Gavi support - a modelling and cost-effectiveness study for Kenya

Introduction: Many low income countries soon will need to consider whether to continue pneumococcal conjugate vaccine (PCV) use at full costs as they transition from Gavi support. Using Kenya as a case study we assessed the incremental cost-effectiveness of continuing PCV use. Methods: We fitted a dynamic compartmental model of pneumococcal carriage to annual carriage prevalence surveys and invasive pneumococcal disease (IPD) incidence in Kilifi, Kenya, and predicted disease incidence and related mortality for either continuing PCV use beyond 2022, the start of Kenya9s transition from Gavi support, or its discontinuation. We calculated the costs per disability-adjusted-life-year (DALY) averted and associated prediction intervals (PI). Results: We predicted that overall IPD incidence will increase by 93% (PI: 72% - 114%) from 8.5 in 2022 to 16.2 per 100,000 per year in 2032, if PCV use is discontinued. Continuing vaccination would prevent 15,355 (PI: 10,196-21,125) deaths and 112,050 (PI: 79,620-130,981) disease cases during that time. Continuing PCV after 2022 will require an estimated additional US$15.6 million annually compared to discontinuing vaccination. The incremental cost per DALY averted of continuing PCV was predicted at $142 (PI: 85 - 252) in 2032. Conclusion: Continuing PCV use is essential to sustain its health gains. Based on the Kenyan GDP per capita of $1445, and in comparison to other vaccines, continued PCV use at full costs is cost-effective. These arguments support an expansion of the vaccine budget, however, affordability may be a concern.