Cost-effectiveness of the Adjuvanted Herpes Zoster Subunit Vaccine in Older Adults

Abstract

Importance: The live attenuated herpes zoster vaccine (ZVL) is recommended for immunocompetent adults 60 years or older, but the efficacy wanes with age and over time. A new adjuvanted herpes zoster subunit vaccine (HZ/su) has higher efficacy but might be more expensive. The choice of vaccines depends on their relative values.

Objective: To assess the cost-effectiveness of HZ/su.

Design, setting, and participants: Markov decision model with transition probabilities based on the US medical literature. Participants were immunocompetent adults 60 years or older. Data were derived from participant groups ranging in number from less than 100 to more than 30 000 depending on the variable assessed. The study dates were July 1 to 31, 2017.

Exposures: No vaccination, ZVL (single dose), and HZ/su (2-dose series) vaccine administered at different ages.

Main outcomes and measures: Total costs and quality-adjusted life-years (QALYs) were estimated.

Results: Based on randomized clinical trial data, at a price of $280 per series ($140 per dose), HZ/su was more effective and less expensive than ZVL at all ages. The incremental cost-effectiveness ratios compared with no vaccination ranged from $20 038 to $30 084 per QALY, depending on vaccination age. The finding was insensitive to variations in most model inputs other than the vaccine price and certain combinations of low adherence rate with a second dose and low efficacy of a single dose of HZ/su. At the current ZVL price ($213 per dose), HZ/su had lower overall costs than ZVL up to a price of $350 per 2-dose series. In probabilistic sensitivity analysis, HZ/su had 73% probability of being cost-effective for 60-year-olds at $50 000 per QALY.

Conclusions and relevance: Under conservative assumptions, at a price of $280 per series ($140 per dose), HZ/su would cost less than ZVL and has a high probability of offering good value.

Figure 1.. Tornado Diagram of the Incremental Cost-effectiveness Ratio (ICER) of the Adjuvanted Herpes Zoster Subunit Vaccine (HZ/su) at Vaccination Age of 60 Years

Ranges are in parentheses, with the left values leading to the leftmost ICERs. BOI indicates burden of illness; HZ, herpes zoster; PHN, postherpetic neuralgia; QALY, quality-adjusted life-year; and ZVL, live attenuated herpes zoster vaccine. ICER values are given in 2016 US dollars. ^aRanges for these age-specific parameters are listed in Table 1, with the highest values leading to the leftmost ICERs. ^bIncidences in both men and women were varied at the same time with ranges listed in Table 1.

Figure 2.. Two-Way Sensitivity Analysis at Vaccination Age of 60 Years With a Willingness-to-Pay Threshold of $50 000 per Quality-Adjusted Life-year

A-C, Letter x denotes base case. HZ/su indicates adjuvanted herpes zoster subunit vaccine; ZVL, live attenuated herpes zoster vaccine. Costs are given in 2016 US dollars.

Figure 3.. Probability of Each Strategy Being Cost-effective at Different Willingness-to-Pay Thresholds

A-C, Probabilistic sensitivity analysis. HZ/su indicates adjuvanted herpes zoster subunit vaccine; QALY, quality-adjusted life-year; and ZVL, live attenuated herpes zoster vaccine. Costs are given in 2016 US dollars.