New Analysis Strengthens Evidence of Reduced Risk of Dementia with Shingles Vaccination
Through analysis of historical vaccination program data, researchers have demonstrated a persistent link between the live-attenuated zoster vaccination and a lower incidence of dementia.
New analysis of a historical vaccination program, published in Nature (1), has provided strong evidence that there is a link between the live-attenuated herpes zoster vaccination (Zostavax, Merck) and a reduced risk of dementia. This analysis may have the potential to shape future work, which could lead to a breakthrough in treatment or prevention of dementia.
The study researchers, led by scientists from Stanford University, analyzed electronic health record data from a vaccination program that took place in Wales, UK, from Sept. 1, 2013. The eligibility criterion for the vaccination program was based on year of birth, with those born before Sept. 2, 1933 deemed as ineligible and those born on or after Sept. 2, 1933 identified as eligible for at least one-year to receive the vaccine. It is this unique aspect of the program that has afforded the researchers a balanced comparison between individuals that are only a few weeks apart in age — something that has been missing from other studies based on health records.
“[A]ssociational studies suffer from the basic problem that people who get vaccinated have different health behaviors than those who don’t,” said the study’s lead author, Pascal Geldsetzer, MD, Ph.D., assistant professor of medicine at Stanford University, in a Stanford Medicine News Center article (2). “In general, [associational studies are] seen as not being solid enough evidence to make any recommendations on.”
To be able to isolate the relationship of the vaccination and rate of dementia while avoiding confounding concerns, the researchers focused their analysis on the health data of the adults who just missed out on eligibility for vaccination by one week and those who were just eligible by one week. The health outcomes of the focus group were then reviewed over a seven-year period, which allowed the researchers to not only demonstrate the effectiveness of the vaccine but also determine if those who were vaccinated were less likely to develop dementia.
At the end of the follow up period, in 2020, the researchers’ analysis led them to the conclusion that patients who had received the zoster vaccination were 20% less likely to develop dementia. “It was a really striking finding. This huge protective signal was there, any which way you looked at the data,” added Geldsetzer in the article (2).
Further analysis of the data was performed to ensure all variables were accounted for as much as possible. Even through their extensive work, the researchers found that the link between the vaccination and lower rates of dementia persisted. Furthermore, the work has been replicated in other studies of health data from patients in England, Australia, New Zealand, and Canada, where similar vaccination programs were employed.
The zoster vaccination has been largely discontinued now, with a newer vaccine — a recombinant zoster vaccine (Shingrix, GSK) — being used as the standard in the U.K. and recommended vaccine in the U.S. Work is being undertaken to determine if the recombinant vaccine is also associated with a reduced risk of dementia (3).
References
Eyting, M.; Xie, M.; Michalik; et al. A Natural Experiment on the Effect of Herpes Zoster Vaccination on Dementia. Nature, April 2, 2025.
Bai, N. Study Strengthens Link Between Shingles Vaccine and Lower Dementia Risk. Stanford Medicine News Center, April 2, 2025.
GSK. GSK, UK Dementia Research Institute (UK DRI) and Health Data Research UK (HDR UK) to Collaborate on First-of-its-Kind Dementia Research Initiative. Press Release, March 25, 2025.