A study found that the shingles vaccine reduces the odds of developing dementia by 20%. While it has not been determined exactly how the vaccine prevents dementia, it is presumed to help by overall boosting human immunity.
A research team led by Pascal Geldsetzer, a professor at Stanford University in the U.S., reported in the international journal "Nature" on the 3rd that people in Wales who received the shingles vaccine "Zostavax" from Merck (MSD) had a 20% lower rate of dementia within seven years compared to those who were unvaccinated.
Shingles is a neurological disease caused by infection with the varicella zoster virus. When the virus infects individuals in childhood, they develop chickenpox, characterized by blisters all over the body. If the dormant virus reactivates in adulthood, it leads to shingles, which appears as a rash in a band pattern on the skin. The rash gradually turns into blisters, causing pain. The pain associated with shingles is reportedly comparable to that experienced during childbirth.
The research team analyzed the impact of the shingles vaccine policy in Wales on the odds of developing dementia. Wales has implemented a program since 2013 to vaccinate individuals born on or after September 2, 1993, with the shingles vaccine for one year.
If vaccination against shingles was concentrated among a specific group, it can be viewed as a good case study to understand the impact on dementia rates. In fact, among those born in early September 1993, the vaccination rate was nearly 47.2%, while for those born just a week earlier, the rate was only 0.01%.
The research team analyzed the medical data of 282,541 individuals born between September 1, 1925, and September 1, 1942, to examine differences in dementia rates based on shingles vaccination status. Those who received the shingles vaccine had a dementia rate of 14% by 2020, seven years later, while the rate for the unvaccinated was 17%. A simple comparison shows that vaccination reduced the risk of developing dementia by about 20%.
The preventive effect of the shingles vaccine on dementia has also been confirmed before. A joint research team from the University of Oxford and the London School of Hygiene & Tropical Medicine analyzed medical data from 103,837 individuals vaccinated against shingles between 2017 and 2020 and found evidence of up to a 28% preventive effect against dementia.
However, it remains unclear how the shingles vaccine prevents dementia. Both studies were limited to analyzing medical data. A large-scale clinical trial is needed to ascertain its exact effectiveness. Participants should be randomly assigned to receive either the shingles vaccine or a placebo and monitored over a long period.
Scientists presume that the shingles vaccine helps prevent dementia by boosting immunity. Those infected with the varicella zoster virus in childhood are at a greater risk of developing shingles later in life. The virus can remain dormant in the nerves and proliferate when immunity weakens, triggering shingles symptoms. It notably affects older adults and patients taking immunosuppressants who have weakened immune systems.
Shingles is closely related to dementia. Since the virus remains dormant in the nerves and proliferates, it can also affect the brain. The medical community believes that some of the virus may lie dormant in the brain and could proliferate when immune function declines due to aging, potentially leading to symptoms of dementia that impair cognitive function. If this hypothesis is correct, the shingles vaccine may also prevent dementia by inhibiting the proliferation of the virus dormant in the brain.
Anupam Jena, a professor at Harvard University in the U.S., evaluated the study in a commentary published in Science the same day, stating, "This study provides strong evidence that the shingles vaccine lowers the risk of dementia." He noted that "the shingles vaccine may prevent the reactivation of the virus dormant in the human body" and suggested that it could lower the use of narcotic painkillers due to shingles, helping maintain brain activity while overall boosting immunity and reducing neuroinflammation.
References
Nature (2025), DOI: https://www.nature.com/articles/s41586-025-08800-x
Nature Medicine (2024), DOI: https://doi.org/10.1038/s41591-024-03201-5