FROM JAMA INTERNAL MEDICINE
The novel herpes zoster subunit vaccine (HZ/su) is more effective and less expensive than the currently used live attenuated virus (ZVL), according to a study from the Center for Value-Based Research.
Phuc Le, PhD , of the Cleveland Clinic and her colleague Michael Rothberg, MD , conducted an economic analysis of vaccine strategies from the societal perspective. This included the direct medical costs and productivity losses associated with HZ disease and complications.
The HZ/su vaccine information was derived from two different randomized clinical trials. In the first trial, HZ/su demonstrated a 97% efficacy rate for all age groups in a randomized clinical trial. In the second HZ/su vaccine trial, a similarly high efficacy rate was observed, around 90%.
The one-, two-, and three-way sensitivity analyses examined how different variables affected the cost-effectiveness of different vaccine strategies. The one-way analysis examined the association of input variables and cost-effectiveness. This included HZ/su prices, waning rate and initial efficacy of a dose of HZ/su, and the adherence rate. This analysis revealed that, compared with no vaccination, HZ/su would provide cost savings up to a price of $160, or $80 per dose.
Regardless of circumstance, HZ/su was always more effective than ZVL according to the two-way sensitivity analysis. This analysis took into account the joint effect of price, adherence to two doses of HZ/su, efficacy, and the waning rate of one dose and two doses of HZ/su and ZVL. Compared with ZVL, HZ/su would be less costly up to a price of $350 per series.
Adherence rates to vaccination schedules were important in determining the efficacy and waning rate which ultimately effected cost-effectiveness. The three-way sensitivity analysis found that, if HZ/su adherence to the second dose was greater than 56.8%, results were insensitive to the variation of single-dose efficacy and waning rate of HZ/su. But if adherence rates fell below 40%, combinations of waning rate and lower efficacy made HZ/su cost ineffective. Most importantly, ZVL was never cost effective for 60-year-old patients.
Despite a projected price of $280 per series, HZ/su is still more effective and less expensive than ZVL for adults 60 years or older. According to Dr. Le and Dr. Rothberg, the assumptions about the vaccine’s efficacy duration and price were reasonable. But, if the vaccine price were to rise in the future, or a single dose becomes much less effective than reported by GlaxoSmithKline, or if adherence to the second dose was remarkably low, the results of the study would be changed.
“An ACIP recommendation stating a preference for HZ/su over ZVL could lead to future price increases, which would render the vaccine no longer cost effective” wrote Dr. Le and Dr. Rothberg. “Therefore, a recommendation linked to periodic reassessment of cost-effectiveness based on the vaccine price might help to mitigate the effect of the recommendation on vaccine affordability.”
Dr. Le and Dr. Rothberg reported having no conflicts of interest.
The HZ/su vaccine is not yet approved by the U.S. Food and Drug Administration, but in 2017, the FDA Advisory Committee unanimously voted in favor of its use in adults age 50 years and older.
SOURCE: Phuc L et al. JAMA Intern Med. 2018 Jan 2. doi: 10.1001/jamainternmed.2017.7431 . Najafzadeh M. JAMA Intern Med. 2018. doi: 10.1001/jamainternmed.2017.7442.
