Background: ZOSTAVAX® (zoster vaccine) has been approved in the U.S. for the prevention of herpes zoster (HZ) in persons >= 60 years of age. Recently, a placebo-controlled efficacy trial (ZOSTAVAX Efficacy and Safety Trial, ZEST) demonstrated that the vaccine also reduces the incidence of HZ in persons 50-59 years of age.
Objectives: To evaluate the cost effectiveness of ZOSTAVAX in the United States for persons 50 to 59 years of age.
Methods: We updated a cost effectiveness model previously developed by Pellissier et al. (2007) by utilizing efficacy data from ZEST and other clinical trials as well as economic data from observational studies. We utilized a statistical model of the durability of vaccine efficacy developed by Li et al. (2010) to project the duration of vaccine protection and conducted analyses from both payer and societal perspectives. Sensitivity analyses were performed on parameters identified as influential in previous economic evaluations, including duration of vaccine protection, vaccine efficacy against post-herpetic neuralgia (PHN) and cost of PHN.
Results: For the base case analysis, the cost-effectiveness ratio was ~ US$50,000 per Quality Adjusted Life Year (QALY). Across the sensitivity analyses, the cost-effectiveness ratio ranged from $30,000 to $70,000 per QALY gained. The most influential variables in the analysis included the durability of vaccine efficacy, cost of PHN and vaccine efficacy against PHN.
Conclusions: ZOSTAVAX is likely to be cost-effective in the U.S. for immunocompetent persons 50 to 59 years of age, based on commonly accepted criteria for assessing cost-effectiveness.