HOW MUCH IS IT WORTH TO PREVENT SHINGLES? USING COST-EFFECTIVENESS ANALYSIS TO DETERMINE VALUE-BASED PRICING OF A NEW HERPES ZOSTER VACCINE

Purpose: The live attenuated herpes zoster (HZ) vaccine (LAV) has been recommended for immunocompetent adults aged ≥ 60 years since 2008. However, its efficacy is lower in older patients and wanes completely after 10 years. A new adjuvanted subunit HZ vaccine (ASV) has much higher efficacy at all ages, but long-term efficacy is unknown. The choice of vaccines will depend on their relative values. We used cost-effectiveness analysis to determine value-based pricing of ASV.

Method: We employed a Markov model to assess the cost-effectiveness from the societal perspective of 5 strategies: no vaccine, single dose of LAV, single dose of ASV, LAV with booster, and ASV with booster. A booster of LAV was given at 10 years based on its duration of efficacy. Because the long-term protection was unknown, ASV was assumed to decline at the same rate as LAV and a booster was given at 15 years. We examined patients first vaccinated at 60, 70 and 80 years. Patients entered the model in the ‘Healthy’ state, then transitioned between HZ-related health states until death or age 120. Transition probabilities, costs, and utilities were drawn from the medical literature. Efficacy data were based on clinical trials. Costs included direct medical costs and productivity loss in 2015 $; effectiveness was expressed in quality-adjusted life years (QALYs); both were discounted at 3%/year. We used threshold analysis to determine ASV’s price for use in base-case and sensitivity analyses. In probabilistic sensitivity analysis (PSA), we performed 10,000 Monte Carlo simulations at nine different ASV prices ranging from $200 – $1,000. 

Result: At all ages, ASV was more effective than LAV. At a willingness-to-pay threshold of $100,000/QALY, ASV would justify a price of $639 if the duration of efficacy was 20 years. At this price, the best option was “ASV with a booster” for patients aged 60 and 70 years, and ASV alone for 80-year-olds. Cost-effectiveness depended on the cost of ASV, its long-term efficacy and patient compliance with a booster. In PSA, the ASV had ≥80% probability of meeting the cost-effectiveness threshold at a price of $500.

Conclusion: Under conservative assumptions, at a price of $500 the ASV has a high probability of offering good value for money. Information on its long-term efficacy should influence this value-based price.