Effectiveness and cost-effectiveness of vaccination against herpes zoster in Canada: a modelling study.

Background: Two vaccines against herpes zoster are currently authorized for use in Canada: the recombinant subunit zoster vaccine and live attenuated zoster vaccine. We compared the effectiveness and cost-effectiveness of these 2 vaccines.
Methods: We used a decision analytic static cohort model parametrized with Canadian epidemiologic and economic data. We performed the economic analysis from the health care system perspective, using a lifetime horizon and a 3% discount rate for costs and benefits. The primary outcome was the incremental cost per quality-adjusted life-year (QALY) gained, relative to no vaccination. We ran 30 000 simulations varying all model parameters, including vaccine costs, efficacy and waning.
Results: The number needed to vaccinate (NNV) was higher for the live attenuated zoster vaccine than for the recombinant subunit zoster vaccine for all herpes zoster-related events at all ages. For example, in persons exactly 65 years old, for herpes zoster, median NNV was 21 (90% uncertainty interval [UI] 13-31) versus 8 (90% UI 6-18), and for postherpetic neuralgia, NNV was 64 (90% UI 33-93) versus 31 (90% UI 23-73). For the recombinant vaccine, the median cost-effectiveness ratios varied between cost-saving and $25 881 per QALY gained for adults aged 50 years or older. For the live vaccine, the cost-effectiveness ratios varied between cost-saving and $130 587 per QALY gained and were less than $45 000 per QALY gained only for those 65 to 75 years old. Given its higher efficacy, we estimated that the cost for the complete series of the recombinant vaccine could be $150 to $200 more than the cost of the live vaccine and still be considered cost-effective.
Interpretation: Our model predicted that the recombinant subunit zoster vaccine is likely cost-effective in Canada for adults 60 years or older, and is likely more cost-effective than live attenuated zoster vaccine. These results have informed updated national and provincial recommendations on herpes zoster vaccination.
Competing Interests: Competing interests: Philippe DeWals has received research grants and reimbursement for travel expenses from vaccine manufacturers, including the GSK group of companies, Novartis, Pfizer and Sanofi Pasteur. The quality-adjusted life-year estimates were partially derived from MASTER, a study conducted in 2005–2006 and funded by Merck Frosst Canada Ltd. through a collaborative research agreement between Merck and the study’s scientific steering committee, of which Marc Brisson was a member. No other competing interests were declared.
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