Herpes zoster vaccination and the risk of dementia: A systematic review and meta-analysis.

Introduction: Previous studies have reported a decreased risk of dementia with herpes zoster vaccination. Given this background, this systematic review and meta-analysis aimed to investigate the association between herpes zoster vaccination and the risk of dementia.

Methods: We searched five databases until November 2023 for case-control, cross-sectional, or cohort studies investigating the association of herpes zoster vaccination and dementia. Odds ratios and 95% confidence intervals (95% CIs) were pooled in the meta-analysis. Meta-regression, subgroup, and sensitivity analysis were also conducted.

Results: We evaluated a total of five studies (one cross-sectional, one case-control, and four cohort studies) that included a total number of 103,615 patients who were vaccinated with herpes zoster vaccine. All the studies were of high quality, ranging from 7 to 9. Due to the high heterogeneity (I = 100%, p < .00001) observed in our study, a random effect model was used for the analysis. The pooled odds ratio was 0.84 (95% CI: 0.50, 1.43), p (overall effect) = .53), indicating that herpes zoster vaccination reduces the risk of dementia.

Conclusion: Herpes zoster vaccination is associated with a reduction of the risk of dementia. More epidemiological studies are needed to confirm the association.