BACKGROUND: Immunocompromised (IC) individuals are at increased risk of herpes zoster (HZ) and its complications. Recombinant zoster vaccine (RZV) received regulatory approval for use in the Canadian IC population in 2021. We evaluated the cost-effectiveness and public health impact (PHI) of RZV versus no-vaccination in the Canadian IC population aged ³18 years.
METHODS: The Zoster ecONomic Analysis Immunocompromised (ZONA IC) model was used to follow a base-case scenario cohort of 1,600 patients with hematopoietic stem-cell transplant aged 55 years, who maintain an IC status for 5 years, from a societal perspective. Scenario analyses were conducted for patients with human immunodeficiency virus (HIV), renal transplant, Hodgkin lymphoma and breast cancer. A life-long time horizon and a discount rate of 1.5% for costs and quality-adjusted life-years (QALY) were applied. Coverage was set to 60% and second dose completion rate to 100%. Probabilistic and deterministic sensitivity analyses were run.
RESULTS: In the base case analysis, RZV vaccination prevented 116 HZ and 27 postherpetic neuralgia (PHN) cases respectively compared with no vaccination. The median ICER was CAD21,102 per QALY gained and was most sensitive to assumptions in HZ incidence, direct medical costs, QALY loss due to PHN, RZV efficacy against PHN and waning. Scenario analyses in other IC populations yielded the highest median ICER for people with Hodgkin lymphoma (CAD84,100), followed by HIV (CAD67,207), renal transplant (CAD25,790) and breast cancer (CAD19,284).
CONCLUSION: RZV vaccination in Canada improves public health outcomes and is cost-effective for several IC conditions considering a CAD50,000 willingness-to-pay threshold.
