Shingles Vaccination Helps Some Who Later Develop the Virus

Diana Phillips

June 15, 2015

Prior vaccination against herpes zoster (HZ) among some patients who later develop the virus reduces their risk for postherpetic neuralgia (PHN) compared with those who are not vaccinated, according to results from a new cohort study.

The findings add to a growing body of literature suggesting that the vaccine provides incremental benefits beyond reducing the incidence of HZ, the virus that causes shingles, Hung Fu Tseng, PhD, from the Department of Research and Evaluation, Kaiser Permanente Southern California, Pasadena, and colleagues report in an article published online June 1 in the Journal of Infectious Diseases.

The cohort study included 1155 adults who were vaccinated against HZ when they were aged 60 years or older and who had an episode of the shingles virus after January 1, 2007, and the same number of unvaccinated sex- and age-matched patients who also had the virus after January 1, 2007. Vaccinated female patients in both the 60- to 69-year and 70-year and older groups had a significantly lower risk for PHN than unvaccinated female patients, the authors write. Overall, 4.2% of the vaccinated women experienced PHN compared with 10.4% of the unvaccinated women.

The researchers observed no similar reduced risk among male patients in any age group. In the group of vaccinated men who developed shingles, 6.0% experienced PHN compared with 5.8% of unvaccinated men, the authors report. This "striking sex specific difference" could be attributable to random error, an unrecognized biological phenomenon, or differential healthcare-seeking behaver by sex, they suggest.

For the investigation, trained medical residents reviewed the electronic health records of members of the Kaiser Permanente Southern California health system who met the study criteria to determine the presence of HZ-related pain at 1, 2, 3, and 6 months after HZ diagnosis. The investigators compared the incidence of PHN between vaccinated and unvaccinated patients. The vaccine proved most effective at preventing prolonged episodes of PHN. Specifically, the relative risk for HZ-related pain in women decreased with longer PHN duration (0.6, 0.4, 0.4, and 0.2 for pain at months 1, 2, 3, and 6, respectively).

"This finding is clinically important because patients and providers may be more likely to consider vaccination if it can prevent the most prolonged episodes of PHN," the authors write. "The data suggest that the pathways by which HZ vaccination interferes with development of HZ (ie, boosted cell-mediated immunity), though not sufficient to prevent all HZ, may reduce the severity and duration of the HZ episodes that do occur."

Commenting on the observed sex-specific difference, the authors suggest that sex variations in healthcare-seeking behavior may be a contributing factor. There is "substantial documentation that among patients with chronic pain, women are more likely to seek medical care and request medications," they write. "Indeed, among unvaccinated patients in our study, men had fewer visits for PHN (≥3 months of HZ-related pain) than women (5.8% vs 10.4%)." In contrast, for subjects in the previously reported Shingles Prevention Study, which used active surveillance to inquire about subjects' pain, "men were more likely than women to report HZ-related pain after 3 months."

The uptake of HZ vaccine has recently started to increase, the authors write. "Ideally, as physicians and patients recognize the full benefits of HZ vaccination, more persons will take advantage of the vaccine to decrease the risk of long-term pain and potential disability."

This work was supported by the Centers for Disease Control and Prevention. Dr Tseng and two coauthors received research support from Novartis Vaccine. Another coauthor serves as an unpaid consultant for Merck. All other authors have disclosed no relevant financial relationships.

J Infect Dis. Published online June 1, 2015. Abstract

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