The Advisory Committee on Immunization Practices (ACIP) recommends routinely giving a single dose of live zoster vaccine to immunocompetent patients age 60 and older at their first clinical encounter. The vaccine effectively prevents shingles and postherpetic neuralgia and their associated burden of illness. Although not all insurance companies pay for it yet, it should be offered to all patients for whom it is indicated to increase their health-related quality of life.
IMMUNITY WANES WITH AGE
Shingles, also known as zoster or herpes zoster, is caused by retrograde transport of the varicella zoster virus (VZV) from the ganglia to the skin in a host who had a primary varicella infection (chickenpox) in the past.1 Although shingles is not one of the diseases that must be reported to public health authorities, more than 1 million cases are estimated to occur each year in the United States. From 10% to 30% of people develop shingles during their lifetime.2,3
The elderly are at particular risk of shingles, because immunity to VZV wanes as a part of normal aging. As many as 50% of people who live to age 85 will have shingles at some point in their life.
Moreover, about 20% of patients with shingles develop postherpetic neuralgia,3,4 the pain and discomfort of which can be disabling and can diminish quality of life.5
Antiviral therapy reduces the severity and duration of an episode of shingles but does not prevent postherpetic neuralgia.2,6 Steroids provide additional relief of acute zoster pain, but they do not clearly prevent postherpetic neuralgia either and should be used only in combination with antiviral drugs. Preventing zoster and postherpetic neuralgia by routine vaccination should be a goal in our efforts to promote healthy aging, especially with the increasing number of elderly in our country.7
THE VACCINE IS EFFECTIVE: THE SHINGLES PREVENTION STUDY
The Shingles Prevention Study was a prospective, double-blind trial in more than 38,000 adults, median age 69 years (range 59–99), who were followed for a mean of 3.13 years (range 1 day to 4.9 years) after receiving the zoster vaccine or placebo.8–10
The virus in the vaccine did not elicit shingles in any patient. After vaccination, if lesions did occur, they were from the patient’s native strain, not the vaccine strain.8
The US Food and Drug Administration approved the zoster vaccine in May 2006 for prevention of herpes zoster in people age 60 and older. Zostavax, licensed by Merck, is the only vaccine available for this purpose.11,12 Zoster vaccine is not indicated for treating episodes of shingles or postherpetic neuralgia or for preventing primary varicella infection (chickenpox).
Zostavax does not contain thimerosal, a mercury-based preservative used in other vaccines. Therefore, it must be kept frozen at an average temperature of –15°C (5°F) and should not be used if its temperature rises above –5°C (23°F).13,14 Just before it is given, the vaccine is reconstituted with the supplied diluents and then injected subcutaneously in the deltoid region.12
No booster dose is recommended at present. Also, many cases of herpes zoster occur in people under age 60, for whom there is no recommendation.11,15 Although the vaccine would probably be safe and effective in this younger group, data are insufficient to recommend vaccinating them.16
ZOSTER VACCINE (ZOSTAVAX) IS NOT CHICKENPOX VACCINE (VARIVAX)
Both Zostavax and the chickenpox vaccine (Varivax) are live, attenuated vaccines from the same Oka/Merck strain of the virus, but Zostavax is about 14 times more potent than Varivax (Zostavax contains 8,700–60,000 plaque-forming units of virus, whereas Varivax contains 1,350), and they should not be used interchangeably.14
GIVING ZOSTER VACCINE WITH OTHER VACCINES IN THE ELDERLY
Zostavax can be given either simultaneously with or at any time before or after any inactivated vaccine (such as tetanus toxoid, influenza, pneumococcus). However, each vaccine must be given in a separate syringe at a different anatomic site.17
VACCINATE EVEN IF THE PATIENT DOESN’T RECALL HAVING CHICKENPOX
Even in people who do not recall ever having chickenpox, the rate of VZV seropositivity is very high (> 95% in those over age 60 in the United States).18 The ACIP recommends vaccination whether or not the patient reports having had chickenpox. Serologic testing to determine varicella immunity is not needed before vaccination, nor was it required for entry in the Shingles Prevention Study.
Furthermore, in VZV-seronegative adults, giving the zoster vaccine is thought to provide at least partial protection against varicella, and no data indicate any excessive adverse effects in this population.