Research suggests that the varicella zoster, or shingles, vaccine (VZV) is less effective in older people with untreated depression.
Notably, the investigators found that similarly aged people receiving treatment for depression had a comparable immune response to the vaccine to nondepressed controls.
Because the majority of the treated depressed patients in the study were taking selective serotonin reuptake inhibitors (SSRIs), "our results suggest that central serotoninergic pathways may play a role in regulating CMI [cell-mediated immunity] responses to VZV, consistent with SSRI enhancement of natural killer cell activity," say the authors.
As reported by Michael Irwin (University of California Los Angeles, USA) and colleagues in Clinical Infectious Diseases, 40 older adults (=60 years of age) with major depressive disorder (18 untreated and 22 on medication) and 52 age- and gender-matched controls had VZV-CMI measured before and 6 weeks, 1 year, and 2 years after vaccination with VZV.
Immunity was measured using a VZV-specific responder cell frequency (VZV-RCF) assay. Depressed individuals who were not taking medication had significantly lower VZV-RCF measures at all time points compared with nondepressed controls and treated depressed individuals. Untreated individuals had a nonsignificant 32.9% decrease in VZV-RCF between baseline and 6 weeks, compared with significant 69.7% and 288.1% increases in VZV-RCF in nondepressed controls and treated depressed individuals, respectively.
These findings were not unduly influenced by changes in depressive symptoms or use of medication over the follow-up period, notes the team.
The researchers suggest that SSRI therapy may help boost the immune response of older people given the VZV, as serotonin and other neurotransmitters are known to regulate CMI at the immunologic synapse and to have a direct effect on T cells.
"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," conclude Irwin and team.
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