1. From a model, the incremental cost-effectiveness ratio between Herpes zoster vaccination and no vaccination at age 50 years was over $300,000 per QALY.
2. At a willingness to pay threshold of $100,000 per QALY, the probability that vaccination would be cost-effective was only 3%.
Evidence Rating Level: 2 (Good)
Study Rundown: Herpes zoster (HZ) affects nearly 1 million Americans yearly, with post-herpetic neuralgia (PHN) occurring in up to 30% of patients. Studies have shown that vaccination can reduce incidence of HZ and PHN in persons aged 60 years or older, but that effectiveness decreases over time. In 2011, a live vaccine was licensed for adults aged 50-59, but its overall value is largely unknown. This study sought to expand cost-effectiveness models for the HZ vaccine to include considerations for vaccination at age 50. For every 1000 persons, the model predicted that 25 cases of HZ and 1 case of PHN would be prevented. The incremental cost for vaccination versus no vaccination for adults aged 50 in the U.S. would be over $600 million. Strengths of the study included use of a previously established simulation model and inclusion of U.S. based studies for epidemiology, effectiveness, and cost, but this study is also limited by the lack of long-term vaccine effectiveness data. Overall, with decreased incidence of HZ and PHN in persons aged less than 60 years old and a decreasing efficacy of vaccinations over time, earlier vaccination is likely not cost-effective.
Relevant Reading: CDC Update on Recommendations for Use of Herpes Zoster Vaccine
In-Depth [decision model]: This study utilized a previously established Markov decision model with updated inputs for vaccine related data in the age group 50-59. Utility decrements were assigned for PHN and serious vaccine reactions based on previously derived data. Costs were based on vaccine, administration, and lost patient wages secondary to complications. If the entire U.S. population of persons aged 50 years old in 2013 were vaccinated, 112,652 cases of HZ and 4504 cases of PHN could be avoided, with an incremental cost of $613 million dollars over no vaccination, for an incremental cost-effectiveness ratio (ICER) of $323,456 per QALY. In 10,000 iterations, the mean ICER was $500,754 per QALY (95%CI $93,510 to $1,691,211), with a median of $362,123. Vaccination at age 59 years of age had the highest effectiveness, the lowest cost, and ICER of $113,121 per QALY. If efficacy remained constant for 10 years before beginning to decrease, the ICER would improve to $14,555 per QALY.
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