Incremental clinical and economic impact of recombinant zoster vaccination: real-world data in a budget impact model

BACKGROUND: In 2017, the FDA approved the adjuvanted recombinant zoster vaccine (RZV) for the prevention of herpes zoster (HZ) in immunocompetent adults aged 50 years and older. RZV joined zoster vaccine live (ZVL) as U.S.-marketed vaccines against HZ. The Advisory Committee on Immunization Practices preferentially recommended use of RZV over ZVL. In order to inform population-based decision makers (PBDMs) about the incremental clinical and economic impact of RZV adoption, budget impact (BI) models may be used. Populating such models with national data can inform PBDMs about the incremental value of RZV adoption nationally; however, heterogeneity across health plans requires the inclusion of plan-specific data to ensure the relevance of modeling outcomes for plan-specific decision makers. OBJECTIVE: To investigate the clinical and economic outcomes associated with the adoption of RZV in nationally representative populations with commercial and Medicare coverage and to demonstrate the effect of the heterogeneity of health plans using real-world data from a large, integrated delivery network (IDN). METHODS: We used a publicly available BI model. The model accounts for national and IDN-collected population characteristics (size, age distribution) and epidemiological data (incidence of HZ and complications, HZ recurrence rate), vaccine characteristics from randomized controlled trials and observational studies (efficacy, waning, second dose compliance for RZV, adverse event rate), national costs (vaccine, direct medical for HZ, complications, and vaccine adverse events), and current and anticipated vaccine coverage. We assessed incremental clinical (HZ cases and complications) and economic (per-member-per-month [PMPM] costs) impact at 5-year to 15-year time horizons, comparing scenarios where RZV is solely implemented with one where only ZVL is utilized. RESULTS: Following the adoption of RZV, the incremental HZ cases avoided over 5 and 15 years were estimated to be 1,800 and 15,000 for a commercial plan, 3,800 and 21,000 for a Medicare plan, and 8,600 and 71,000 for a specific IDN. The incremental PMPM budget impact over the same time horizons was estimated to be $0.42 and $0.31, respectively, for a commercial plan, $0.35 and $0.10 for a Medicare plan, and $0.39 and $0.25 for a specific IDN. The differences in results across plans resulted from the population age distribution, the vaccine copay (applied in the Medicare scenario only), the vaccine coverage in the plan, and other plan-specific factors affecting disease epidemiology and costs per case of HZ. CONCLUSIONS: Model projections indicated that RZV adoption avoided HZ cases and related complications, with the PMPM budget impact dependent on plan-specific factors. As health gains increased over time, the incremental costs incurred were found to decrease as the shorter-term costs of adopting the new vaccine were increasingly offset by the longer-term benefits of vaccination.