In 2011 Merck received FDA approval to administer Zostavax (Herpes Zoster/ shingles vaccine) in patients age 50-59. Since 2006 Zostavax has been approved for patients age 60 and older. So why should you wait until 60 to get shingles vaccine? I wondered this and on reading the ACIP update on Zoster Immunization released this August their recommendation to wait until age 60 makes sense. Read on to understand the logic of why waiting is better.
Two major factors were taken into consideration in the ACIP decision to choose age 60 as the optimal age for Zoster vaccination. First is that the immunity benefit from Zostavax does not last indefinitely. Immunity is highest in the first year after immunization and is estimated to decrease each year thereafter until little or no benefit remains 10 years after immunization. Shingles vaccination is a one time only shot so timing is important. Second is that the incidence of both Zoster and post-herpetic neuralgia (pain that lasts longer than 30 days after the onset of shingles) increase significantly with age.
The number of cases of Zoster and post-herpetic neuralgia per 1000 persons per year at age 50 is 4/0.4, at age 60 is 6/1 and at age 70 is 8.5/2.7.
Given this information combined with life expectancy information the ACIP concluded that by giving Zostavax at age 60 would prevent 26.147 zoster cases per million persons vaccinated. Other ways to look at this are that there is a 2.61% chance that getting Zostavax will prevent shingles in any given person, and that the cost to save one quality adjusted life year (QALY) using Zostavax at age 60 9s $87,000. At age 50 the numbers are 19795 cases prevented per 1,000,000 persons at age 50 and 21269 per 1,000,000 at age 70. Because the incidence of postherpetic neuralgia is so much higher at age 70 the cost of quality adjusted life year saved would by much less if Zostavax is given at age 70, at $37,000/QALY and much higher if given at age 50 at $287,000/ QALY saved.
Prior to reviewing this data I have been following the USPSTF/ACIP recommendation to recommend Zostavax at age 60, but had willingly have offered the vaccine to patients age 50-59 who requested vaccination. Now I explain the benefits of waiting and most patients happily postpone vaccination until 60.
Bottom line is that the ACIP recommendatilon to wait until age 60 to get Zostavax makes lots of sense and is pretty easy to explain to patients in a way that makes sense to them too. This recommendation could change if future studies show that a second dose of Zostavax is found to be safe and effective and is recommended.