Shingles Vaccine Effective but Underused in Elderly

Norra MacReady

April 12, 2013

Despite compelling evidence that the shingles vaccine is effective in elderly adults, clinical use of the vaccine remains "disappointingly low," a new study shows.

Lead author Sinéad M. Langan, MD, from the Department of Epidemiology and Population Health, London School of Hygiene and Tropical Medicine, United Kingdom, and colleagues studied the vaccine in a randomly chosen group of Medicare enrollees. The vaccine's effectiveness has previously been documented in selected insured populations and among people with certain immune-mediated conditions, "but not among an unselected population in a clinical setting," the authors explain in their article, published online April 9 in PLOS Medicine.

From January 1, 2007, through December 31, 2009, the researchers studied people aged 65 years or more drawn from the 5% random Medicare Standard Analytic Files, which provides a random sample of Medicare beneficiaries and identifies patients who receive the herpes zoster vaccine. Incident cases of herpes zoster were identified by examining patient records for the International Classification of Diseases, Ninth Revision, Clinical Modification, code for herpes zoster, coinciding with use of antiviral medication, as determined from Medicare part D records. The authors also tracked the incidence of postherpetic neuralgia (PHN) related to the herpes zoster diagnoses.

"This is the first study to the best of our knowledge to assess the effectiveness of herpes zoster vaccine against both incident herpes zoster and PHN in an unselected older population including those with immunosuppression," the authors state.

Of the 766,330 study participants, only 29,785 (3.9%) were vaccinated during the study period. Rates were particularly low among people who were black, of low income, or aged 80 years or more. There were 12,958 cases of herpes zoster infection among unvaccinated individuals compared with 154 cases among people who had been vaccinated. After adjusting for age, sex, race, income, and several chronic inflammatory and immune-mediated illnesses, the hazard ratio for incident herpes zoster associated with the vaccine was 0.52, with 95% confidence intervals (CI) of 0.44 to 0.61. Among immunosuppressed patients, there were 1560 cases in unvaccinated people compared with 24 in those who were vaccinated, for an adjusted hazard ratio of 0.63 (95% CI, 0.42 - 0.94).

Similarly, 1665 cases of PHN occurred among unvaccinated individuals within 30 days of the zoster diagnosis compared with 16 in those who received the vaccine, for an adjusted hazard ratio of 0.38 (95% CI, 0.23 - 0.63). Extending that analysis out to 90 days resulted in another 871 cases of PHN documented among unvaccinated people, but none in those who were immunized, for an adjusted hazard ratio of 0.41 (95% CI, 0.21 - 0.79).

"[The findings] show that shingles vaccination is effective against incident shingles in a general population of older individuals, including those who are immunosuppressed, and suggest that shingles vaccination is effective against post-herpetic neuralgia," the authors conclude.

Study limitations include reliance on administrative data and lack of randomization.

"Despite these limitations, these findings provide useful information for policy makers in countries that are currently considering the introduction of shingles vaccination into routine practice," the authors write. "Moreover, they highlight the need to increase shingles vaccination among elderly individuals in the US, the section of the population at the highest risk of post-herpetic neuralgia."

Experts Agree: Vaccine Should Be Promoted

Two independent observers agreed that physicians should be doing more to promote the vaccine among their elderly patients. Hung Fu Tseng, PhD, MPH, senior scientist in the Department of Research and Evaluation, Kaiser Permanente of Southern California, told Medscape Medical News that "the low vaccination uptake in the general population indicates the need to reduce barriers to the vaccine, such as financial cost, storage requirements, and accessibility."

"This study reinforces the belief that the vaccine works in real life," added Marla Shapiro, MD, associate professor of family and community medicine at the University of Toronto, Ontario, Canada. "Shingles and [PHN] are among the most common forms of neurologic disability in the elderly, and primary preventive strategies are critical, because treatment opportunities are modest at best."

"Papers like this are critical to point out the real-life efficacy of the vaccine and its importance in this population," she added.

The study was supported by the National Institute for Health Research, United Kingdom, Department of Health. One study author has been a consultant for GlaxoSmithKline, and another author has been on separate data safety monitoring boards for Abbott and Astellas. Dr. Shapiro is on the Merck speakers bureau and has received financial support from the SIGMA Canadian Menopause Society through an unrestricted grant from Merck. The other study authors and Dr. Tseng have disclosed no relevant financial relationships.

PLOS Med. Published online April 9, 2013. Full text

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