HealthDay News — Elderly patients with untreated major depression have a diminished response to the shingles vaccine, researchers found.

Patients with major depressive disorder who were not receiving antidepressants had lower cell-mediated immunity to the varicella zoster virus (VZV) vaccine than both healthy and depressed individuals who were receiving drug treatment (P<0.01 for both), mostly with selective serotonin reuptake inhibitors (SSRIs), according to Michael Irwin, MD, of the UCLA Semel Institute for Neuroscience, and colleagues.

“Because the incidence and severity of herpes zoster and its complications, particularly postherpetic neuralgia, are increased in persons with depressed cell-mediated immunity to VZV, persons with untreated depression may be at greater risk for herpes zoster and its complications than either nondepressed adults of similar age, sex, and medical comorbidity or depressed persons receiving antidepressants,” the researchers wrote in Clinical Infectious Diseases.

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Irwin and colleagues studied the immune response to VZV immunization in 40 elderly patients (mean age 68) with major depression or other mental illness and 52 age- and sex-matched controls without depression, who participated in the depression substudy of the Shingles Prevention Study.

Among patients with major depressive disorder, 18 were taking antidepressants and 22 were not; both groups had similar depressive symptom severity scores throughout the study. 

Cell-mediated immunity to VZV was measured before vaccination and at six weeks, one year and two years after vaccination.

After adjusting for age, sex, and medical comorbidity, depressed patients who were not taking antidepressants had a statistically significantly lower immune response to VZV compared with non-depressed controls or depressed patients receiving antidepressants, even when antidepressants failed to relieve depression symptoms.

Six weeks after vaccination, immune responses were similar among depressed patients who were being treated with antidepressants and healthy controls. 

“[A]mong depressed elderly persons, treatment with SSRI might increase the efficacy of zoster vaccine and, possibly, vaccines against other important pathogens, such as influenza viruses,” the researchers concluded.

They hypothesized that several factors, such as psychological stress, intercurrent viral infection and alcohol use, which are known to be associated with depression, may play a role in cell-mediated immunity to VZV.

The researchers acknowledged the limitations of the study’s small sample size, but noted that conducting a larger confirmation study may be challenging due to low rates of herpes zoster.


  1. Irwin M et al. Clin Infect Dis 2013; DOI: 10.1093/cid/cis1208.