(HealthDay News) – Depressed elderly patients display a diminished varicella zoster virus (VZV)-specific immune response after vaccination with the herpes zoster vaccine compared with non-depressed patients, but antidepressant medication helps to normalize this response, according to a study published online Feb. 13 in Clinical Infectious Diseases.

Michael R. Irwin, MD, of the University of California in Los Angeles, and colleagues studied the immune response to VZV immunization in 40 elderly patients with major depression or other mental illness and 52 age- and sex-matched controls without depression. The authors sought to determine how depression and antidepressant medication use may affect immune response at six weeks and one and two years after vaccination.

The researchers observed a statistically significantly lower immune response to the VZV vaccine in depressed people compared with non-depressed controls or depressed patients receiving antidepressants, even when antidepressant medications failed to relieve depression symptoms.

“In this study, depressed elderly adults who are not being treated with an antidepressant (i.e., selective serotonin reuptake inhibitor [SSRI]) had a diminished capacity to develop increased levels of VZV-cell-mediated immunity in response to zoster vaccine compared to non-depressed controls and depressed individuals receiving antidepressants,” the authors write. “Thus, among depressed elderly persons, treatment with SSRI might increase the efficacy of zoster vaccine and, possibly, vaccines against other important pathogens, such as influenza viruses.”

One author disclosed financial ties to Merck.

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