Public Health Impact and Cost-Effectiveness of Non-live Adjuvanted Recombinant Zoster Vaccine in Canadian Adults

Plain Language Summary More than 95% of adults aged 50 are infected with varicella-zoster virus and are at risk of developing herpes zoster, also known as shingles. This risk is higher in older people and in people with a reduced immune system. Shingles causes a painful rash and may trigger persistent pain and other complications that greatly reduce quality of life. In Canada, Zostavax is the only existing approved vaccine against shingles. It has been offered in a publicly funded program in Ontario to those aged 65-70 years since September 2016. Shingrix, is a new shingles vaccine that has recently been approved by Health Canada for adults aged >= 50 years. The present model suggests that Shingrix confers higher protection against shingles compared to Zostavax, with a greater reduction in shingles episodes. The increase in vaccination costs would be partially offset by reduced healthcare visit and medication expenses. For these reasons, provincial health plans may consider offering Shingrix to people aged >= 50 years. Objectives In Canada, incidences of herpes zoster (HZ) and postherpetic neuralgia (PHN) are increasing, posing a significant burden on the healthcare system. This study aimed to determine the public health impact and cost effectiveness of an adjuvanted recombinant zoster vaccine (RZV) compared to no vaccination and to the live attenuated vaccine (ZVL) in Canadians aged 60 years and older. Methods A multi-cohort Markov model has been adapted to the Canadian context using recent demographic and epidemiologic data. Simulations consisted of age-cohorts annually transitioning between health states. Health outcomes and costs were discounted at 1.5% per year. The perspective of the Canadian healthcare payer was adopted. A coverage of 80% for the first RZV and ZVL dose and a compliance of 75% for the second RZV dose were assumed. Results RZV was estimated to be cost effective compared with no vaccination with an incremental cost-effectiveness ratio (ICER) of $28,360 (Canadian dollars) per quality-adjusted life-year (QALY) in persons aged >= 60 years, avoiding 554,504 HZ and 166,196 PHN cases. Compared with ZVL, RZV accrued more QALYs through the remaining lifetime and an increase in costs of approximately $50 million resulting in an average ICER of $2396. Results were robust under deterministic and probabilistic sensitivity analyses. HZ incidence rate and persistence of vaccine efficacy had the largest impact on cost effectiveness. Conclusions The cost-utility analysis suggested that RZV would be cost effective in the Canadian population compared with no vaccination and vaccination with ZVL at a willingness-to-pay threshold of $50,000.