Untreated depression in older adults may be linked to decreased effectiveness of the varicella zoster virus vaccine, according to a study.
Older adults are known to be at risk for herpes zoster, and more than a million new cases occur each year in the United States, according to background information in the study, which is scheduled for publication in the journal Clinical Infectious Diseases.
In a two-year study led by Michael Irwin, MD, at the University of California, Los Angeles, researchers measured the immune responses to varicella zoster virus vaccination among 40 subjects ages 60 and older with a major depressive disorder and compared these responses with similar levels in 52 control patients matched by age and gender. Measurements were taken at baseline, and then six weeks, a year or two years after the patients received the vaccine or a placebo.
Depressed patients not being treated with selective serotonin uptake inhibitors had lower cell-mediated immunity to the varicella zoster virus, and were less able to respond to the vaccine, compared with patients who were not depressed or who were depressed but were receiving treatment with SSRIs, the researchers found.
The findings suggest that patients with untreated depression were “poorly protected by shingles vaccination,” Irwin said in a news release. Depression treatment, on the other hand, boosted cell-mediated immunity and increased the effectiveness of the vaccine among those studied, even when the treatment did not lessen depression symptoms, the researchers found. Treating depression, Irwin noted, appeared to “normalize the immune response to the zoster vaccine” among patients in the study.
Larger studies are needed to evaluate the possible relationship between untreated depression and the risk of varicella zoster virus, the researchers noted, along with research to establish what mechanisms are responsible for patients reduced immune responses. The possible connection, however, is potentially significant: If antidepressants increase the efficacy of the varicella zoster virus vaccine in those who are depressed, such treatment may have a similar effect on the immune responses of depressed patients to other important vaccines, such as those against influenza, the researchers said.
Diagnosis and treatment of depression in older adults may increase the effectiveness of the varicella zoster virus vaccine and help diminish the risk of herpes zoster, the study authors concluded. “Efforts are also needed to identify and diagnose depressed elderly patients who might benefit from either a more potent vaccine or a multi-dose vaccination schedule,” Irwin said.
The study abstract is available at http://cid.oxfordjournals.org/content/early/2013/02/12/cid.cis1208.abstract.