Pharmacology Update
Zoster Vaccine Live (Oka/Merck)
By William T. Elliott, MD, FACP, and James Chan, PhD, PharmD, Dr. Elliott is Chair, Formulary Committee, Northern California Kaiser Permanente; Assistant Clinical Professor of Medicine, University of California, San Francisco; Dr. Chan is Pharmacy Quality and Outcomes Manager, Kaiser Permanente, Oakland, CA. Drs. Chan and Elliott report no financial relationships to this field of study.
The FDA has licensed a new vaccine to reduce the risk of shingles in the people 60 years of age and older. The vaccine is a live, attenuated, Oka/Merck strain of varicella zoster virus (VZV). It is marketed by Merck and Co., Inc. as Zostavax®.
Indications
VZV vaccine is indicated for prevention of herpes zoster (shingles) in individuals 60 years of age and older.1
Dosage
VZV vaccine is administered as a single subcutaneous injection. The vaccine should be administered immediately after reconstitution.
Potential Advantages
VZV vaccine reduces the burden of illness, the incidence of herpes zoster, and reduces the incidence of postherpetic neuralgia.1,2
Potential Disadvantages
Common adverse events include injection site reactions (erythema, pain, tenderness, swelling, pruritus). There is a theoretical risk of transmitting the vaccine virus to varicella-susceptible individuals. The vaccine reduces the herpes-associated events but does not prevent them. Protection has been demonstrated through 4 years; the duration of protection is not known.1
Comments
The efficacy of the vaccine was demonstrated in a trial of over 38,000 adults 60 years of age or older.1,2 The median follow up time was 3.1 years (range, 31 days to 4.9 years) Zoster cases were confirmed primarily by polymerase chain reaction (93%). A single dose of the vaccine reduced the incidence of shingles by 51% (95% CI, 44%-58%). Efficacy appears to lessen with older age. Incidence of postherpetic neuralgia was reduced by 66.5% (95% CI, 47.5-79.2%). Burden of illness, based on a herpes-zoster severity-of-illness score, was reduced by 61% (95% CI, 51.1%-69.1%). In subjects who developed herpes zoster post-vaccination, subsequent postherpetic neuralgia was reduced by 39% (95% CI, 7- 59%). The duration of pain and discomfort was slightly shorter with vaccine recipients, 21 days vs 24 days. The vaccine appears to be well tolerated with injections site reactions being the most common.
Clinical Implications
Shingles is caused by the same virus that causes chicken pox and is due to reactivation of latent varicella-zoster virus within the sensory ganglia.3 The incidence and severity increases with age. Post herpetic neuralgia is the most frequent complication of herpes zoster and similarly the frequency and severity increase with age. The VZV vaccine appears to be effective in reducing the incidence of shingles and post herpetic neuralgia.
References
1. Zostavax Product Information. Merck & Co., Inc. May 2006.
2. Oxman MN, et al. A vaccine to prevent herpes zoster and postherpetic neuralgia in older adults. N Engl J Med. 2005;352:2271-2284.
3. Weller TH. Varicella and herpes zoster. Changing concepts of the natural history, control, and importance of a not-so-benign virus. N Engl J Med. 1983;309:1434-1440.
The FDA has licensed a new vaccine to reduce the risk of shingles in the people 60 years of age and older.You have reached your article limit for the month. Subscribe now to access this article plus other member-only content.
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