Clinical question
What are the benefits of the zoster vaccine?
Evidence
Two large industry-supported multicentre RCTs of zoster vaccine or placebo vaccine:
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One RCT of 38 546 immunocompetent patients aged 60 years or older (median age 69 years, 59% male).1 Outcomes at 3 years:
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- Zoster (herpes zoster [HZ], shingles) incidence
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— vaccine 1.67%, placebo 3.42%; NNT = 58.
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- Postherpetic neuralgia (PHN) incidence
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— vaccine 0.14%, placebo 0.42%; NNT = 358.
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- Seven-year outcomes of a subgroup of patients were not helpful, as all placebo patients were offered the vaccine, and the numbers are difficult to interpret.2
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One RCT of 22 439 immunocompetent patients aged 50 to 59 years (mean age 55 years, 62% female).3 Followed for 1.3 years:
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- Zoster incidence
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— vaccine 0.27%, placebo 0.88%; NNT = 164;
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— conversion to 3 years, NNT = 71.
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- Limitations: short follow-up; PHN rates not reported.
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Adverse events: about 2% more patients had systemic adverse events with the vaccine,1,3,4 and serious adverse events were also slightly more common (1.9% vs 1.3%).1
Context
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Although the vaccine reduces the relative risk of HZ by 50% to 70%, 60 to 70 patients must be vaccinated to prevent 1 case of HZ over 3 years.1,3
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Rates of HZ increase with age: 3/1000 per year in those 40 to 64 years; 7.5/1000 per year in those 75 and older.5
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Recurrence of HZ is low,1,8 but might be as high as 5.7% over 7 years if including immunocompromised patients.9
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Zoster vaccine guideline recommendations -Canada: vaccinate those 60 years of age and older; can vaccinate those 50 to 59 years old.10
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United States: vaccinate those 60 years of age and older; do not recommend vaccinating those 50 to 59 years old (owing to vaccine supply issues).11
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The cost of the vaccine is about $200.
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Remaining questions about the vaccine:
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- Is it safe and effective in immunocompromised patients?
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- Is it beneficial for patients with previous HZ?
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- What is the long-term efficacy (will a booster be required)?
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Bottom line
Over 3 years, zoster vaccine will prevent 1 HZ case for every 60 to 70 patients vaccinated (and 1 PHN case in 350 vaccinated patients). Long-term benefits and effectiveness in specific populations (eg, the immunocompromised, those with previous HZ) are unclear.
Implementation
Reminders in the electronic medical record appear to increase zoster vaccine uptake12; however, these do not promote shared, informed decision making. Detailed numeric information is necessary.13 For average patients, 1 of every 60 to 70 of those vaccinated will avoid an HZ case over 3 years. Patients with immune-mediated diseases or who are taking immunosuppressive medication have 1.5 to 2 times the risk of developing HZ14; thus, it might be reasonable to more strongly encourage vaccination in those initiating immunosuppressive therapy in the near future.
Notes
Tools for Practice
Tools for Practice articles in Canadian Family Physician (CFP) are adapted from articles published on the Alberta College of Family Physicians (ACFP) website, summarizing medical evidence with a focus on topical issues and practice-modifying information. The ACFP summaries and the series in CFP are coordinated by Dr G. Michael Allan, and the summaries are co-authored by at least 1 practising family physician and are peer reviewed. Feedback is welcome and can be sent to toolsforpractice{at}cfpc.ca. Archived articles are available on the ACFP website: www.acfp.ca.
Footnotes
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The opinions expressed in Tools for Practice articles are those of the authors and do not necessarily mirror the perspective and policy of the Alberta College of Family Physicians.
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