Herpes Zoster Vaccine May Effectively Prevent Dementia

A large natural experiment study in Ontario, Canada, found that receiving the live attenuated herpes zoster vaccine significantly reduced the risk of a new dementia diagnosis by approximately 18% in adults aged 70 and older, providing the strongest evidence to date for a potential causal protective effect. The research leveraged a policy threshold where public funding for the vaccine was determined by birthdate (on or before January 1, 1946, or 1945), comparing the health outcomes of nearly identical groups born immediately on either side of this cutoff. Those eligible for vaccination had an absolute reduction in dementia risk of 2.0 percentage points over a 5.5-year follow-up period. The findings were further strengthened by a cross-province comparison showing that eligible birth cohorts in Ontario had significantly lower dementia incidence after the vaccination program began than matched cohorts in provinces without such a program. This evidence points to a promising public health strategy and suggests that investigating the neuroimmune mechanisms involved could offer new insights into dementia pathophysiology. Source: https://www.thelancet.com/