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ABSTRACT & COMMENTARY

Zoster Vaccine Works — If People Get It

June 1, 2013
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By Stan Deresinski, MD, FACP, FIDSA, Clinical Professor of Medicine, Stanford University, Hospital Epidemiologist, Sequoia Hospital, Redwood City, CA, Editor of Infectious Disease Alert.

Synopsis: In a 5% random Medicare sample to examine the uptake and efficacy of the herpes zoster vaccine in the general population, including immunocompromised individuals — the adjusted vaccine efficacy for protection against herpes zoster was 0.48 (95% CI, 0.39 to 0.56). Among individuals who were immunocompromised, vaccine efficacy was 0.37 (95% CI, 0.06 to 0.58). Protection against the development of post-herpetic neuralgia was also demonstrated by a vaccine efficacy of 0.59 (95% CI, 0.21 to 0.79)

Source: Langan SM, Smeeth L, Margolis DJ, Thomas SL. Herpes zoster vaccine effectiveness against incident herpes zoster and post-herpetic neuralgia in an older US population: a cohort study. PLoS Med 2013 Apr 9; 10:e1001420.

Randomized trials in the U.S. have demonstrated that Zostavax, a high titer live attenuated varicella zoster vaccine reduced the risk of herpes zoster by approximately one-half and the risk of post-herpetic neuralgia by approximately two-thirds. The Centers for Disease Control and Prevention recommends that, in the absence of contraindications, all individuals >60 years of age should receive the vaccine. Although it also has received FDA approval for individuals 50-59 years of age, CDC has not made a recommendation for this cohort. Despite the recommendation for those >60 years of age and coverage by Medicare Part D, the use of the vaccine has appeared to be limited. Langan and colleagues have now used a 5% random Medicare sample to examine the uptake and efficacy of the vaccine in the general population, including immunocompromised individuals.

Of the 766,330 participants, only 3.9% had been vaccinated during the study period(2007-2009). Vaccination rates were especially low in the oldest patients, in African-Americans (0.3%), and in those in the lowest socioeconomic groups (0.6%). Herpes zoster occurred during the study period in 13,112 individuals. The incidence rate per 1000 person-years in vaccinated individuals was 5.4 (95% CI, 4.6 to 6.4) and 10.0 (95% CI, 9.8 to 10.2) in those who had not received the vaccine. As a consequence, the adjusted vaccine efficacy for protection against herpes zoster was 0.48 (95% CI, 0.39 to 0.56). Among individuals who were immunocompromised, vaccine efficacy was 0.37 (95% CI, 0.06 to 0.58). Protection against the development of post-herpetic neuralgia was also demonstrated by a vaccine efficacy of 0.59 (95% CI, 0.21 to 0.79).

Commentary

This very large population-based study confirms the results of randomized trials in more selected populations, with evidence of significant protection against both shingles and post-herpetic neuralgia. Furthermore, the vaccine was also effective in immunocompromised individuals, a group for whom CDC still recommends against vaccination.

In addition to confirming the efficacy of the vaccine, this study also confirms its lack of use. Herpes zoster affects a million individuals yearly in the US, many of whom develop post-herpetic neuralgia and, as a consequence, it has serious health, quality of life, and cost consequences. Barriers to greater use of Zostavax include lack of prescriber and patient knowledge, cost, lack of Medicare eligibility for most before age 65 years, and lack of coverage by some third party payers and state Medicaid systems. We need a medical care system in the United States.