Farmin Shahabuddin, MPH, National Center for Health Research
Alzheimer’s Disease and other forms of dementia affect millions of older adults, and because there is no cure, researchers are working hard to understand how to prevent or delay it. One surprising area of hope is the shingles vaccine. After a person recovers from chickenpox, the virus that caused the disease stays in the body for life and can reactivate years later as shingles, a painful rash caused by inflammation of the nerves. A shingles vaccine, which is recommended for adults aged 50 and older, prevents the virus from reactivating. In recent years, researchers have studied whether it might also reduce inflammation that contributes to dementia. The good news is that it can!
Several large studies from the United States, Canada, the United Kingdom, and Wales have evaluated whether people who get the shingles vaccine have a lower chance of developing dementia or if the vaccine could slow the progression of dementia. These well-designed studies kept track of adults for many years after being vaccinated to understand whether the vaccine helps prevent Alzheimer’s or other types of dementia.
Understanding the Two Shingles Vaccines
There are two different shingles vaccines. The newer vaccine, Shingrix, is now the only shingles vaccine available in the U.S. and is recommended for adults aged 50 and older. Shingrix is a recombinant vaccine introduced in 2017, which means it does not contain a weakened virus. Instead, it uses a piece of the shingles virus combined with a booster ingredient (called an adjuvant) that helps the immune system respond more strongly. Shingrix provides much stronger and longer-lasting protection against shingles than the older vaccine, Zostavax.[1]
Zostavax used a weakened form of the same virus. It was introduced in 2006 and used for many years in the United Kingdom and the United States but was discontinued in the U.S. as of 2020[1] and the company has stopped making it.[2] Most of the earlier research on shingles vaccines and dementia was based on Zostavax, but more recent studies have examined Shingrix. Studies of Zostavax found it helped prevent or delay dementia, and since Shingrix is the vaccine recommended now, we will focus on it first.
Shingrix May Lower the Chance of Dementia
Experts studied about 510,000 adults aged 66 and older who had recently stayed in a nursing home for short-term or long-term care. None of them had dementia when the study started. [3] The study compared people who got at least one dose of the Shingrix shingles vaccine within 12 months of entering the nursing home with people who did not get the vaccine at all.
The participants were followed for up to 4 years to see who developed any type of dementia during that time. By the end of those 4 years, about 19% of the people who got the vaccine had developed dementia, compared with about 25% of the people who did not get the vaccine. In other words, the people who got the vaccine were a little less likely to develop dementia over those 4 years. The apparent benefit was smaller in men, and in people who had previously gotten the older version of the shingles vaccine, Zostavax, which may have already given them some protection. Although experts explain that this one study cannot prove the vaccine helped prevent dementia, it adds to growing evidence that shingles vaccines may help protect the brain from dementia.
Let’s look at the other studies with similar results. A 2024 study published in Nature Medicine followed more than 207,000 adults aged 65 and older in the U.S. who did not have dementia at the start of the study. [4] Researchers compared people who got the Shingrix vaccine with people who got the older Zostavax vaccine and followed them for up to six years to see who developed any type of dementia, including Alzheimer’s disease. Among the adults who developed dementia, people who got Shingrix were diagnosed with dementia an average of 164 days later than people who got the Zostavax vaccine. In addition, women who got the Shingrix vaccine delayed a dementia diagnosis for longer than the men who got the same vaccine. Researchers recommend that more clinical trials should be conducted to confirm these results.
Some experts have tried to understand why the shingles vaccine might help the brain. A 2025 study examined whether an ingredient called AS01 that is found in both Shingrix and a vaccine for respiratory syncytial virus (RSV), might help protect against dementia. [5] Researchers followed more than 436,000 adults aged 60 and older in the U.S. who did not have dementia at the start of the study. They compared people who received the shingles vaccine, the RSV vaccine, both vaccines, and just the flu vaccine (which does not contain AS01) for up to 18 months to see who developed any type of dementia, including Alzheimer’s disease.
Fewer people who received Shingrix or the RSV vaccine developed dementia in the 18 months of the study than people who got only the flu vaccine. Among those who developed dementia, people who got Shingrix were diagnosed with dementia 53 days later than those who got only the flu vaccine. People who got the RSV vaccine were diagnosed 87 days later than those who got only the flu vaccine, and people who received both vaccines were diagnosed about 113 days later than those with only the flu vaccine. That benefit can also be described as 37% more dementia-free days. The study results were similar in men and women. Since both vaccines that contain AS01 showed similar benefits, researchers believe the AS01 ingredient may be helping to protect the brain, rather than simply preventing shingles or RSV infections. Since this study only lasted 18 months, very few of the people in the study developed dementia and any benefit from the vaccines might be more obvious after a longer period of time.
Earlier Research on Zostavax
The study comparing Shingrix with Zostavax is important because several large studies showed the Zostavax vaccine also helped protect against dementia. A 2025 study in Wales followed more than 300,000 adults aged 71 to 88 for 7-9 years and found that adults vaccinated with Zostavax were slightly less likely to show early cognitive decline and were 8% to 9% less likely to die from dementia-related causes.[6] A 2023 UK study followed more than 8 million adults aged 70 and older for an average of 3 years. [7] It found that adults vaccinated with Zostavax were about 22% less likely to be diagnosed with dementia than adults who did not get it. The vaccine was less effective at reducing the chances of developing Alzheimer’s (a 9% decrease) than reducing other forms of dementia (a 29% decrease).
A recent study examined data from more than 232,000 adults in Ontario, Canada, and followed them for 5.5 years. In 2016, Ontario began offering the free Zostavax shingles vaccine to adults aged 65 to 70. Rather than studying vaccinated adults vs. those who were not vaccinated, these researchers compared two groups of patients who were almost identical in age, nearly 70 when the study began: one group was just young enough to qualify for the free vaccine when the program began, and the other was just past the age limit and could not receive it. It found that the adults who were eligible for the free vaccine were 20% less likely to develop dementia compared to those who were just past the age limit.[8]
Although Zostavax is no longer available, these studies helped establish that shingles vaccination can help prevent or delay dementia and that Shingrix may be more beneficial than Zostavax
The Bottom Line
The shingles vaccine is not a cure for dementia and does not always prevent it, but neither do any of the expensive medications that are being promoted for people who show possible signs of dementia. However, the studies so far consistently show that adults who get the shingles vaccine are less likely to develop dementia, may delay the onset of symptoms, and may even slow disease progression if they already have early dementia.
Since Shingrix is already recommended for adults aged 50 and older to prevent the painful disease of shingles, these additional benefits offer another good reason to get vaccinated. The CDC recommends Shingrix for all adults age 50 and older, and for adults 19 and older with weakened immune systems. It is given as a series of two shots. To learn more, check the CDC website on shingles vaccination.
References:
- Centers for Disease Control and Prevention. (2024). Shingles (herpes zoster): Vaccine considerations for healthcare providers. https://www.cdc.gov/shingles/hcp/vaccine-considerations/index.html
- European Medicines Agency. (2025, June 11). Zostavax: EPAR – Summary for the public. https://www.ema.europa.eu/en/medicines/human/EPAR/zostavax
- Hayes, K. N., Harris, D. A., McConeghy, K. W., Grove, L. R., Joshi, R., Han, L., Davidson, H. E., Chachlani, P., Bayer, T. A., Singh, M., Abul, Y., DeVone, F., & Gravenstein, S. (2026). Dementia risk after recombinant herpes zoster vaccination in older adults with a recent skilled-nursing facility stay: A target trial emulation. Annals of Internal Medicine. Advance online publication. https://doi.org/10.7326/ANNALS-25-04689
- Taquet, M., Dercon, Q., Todd, J. A., & Harrison, P. J. (2024). The recombinant shingles vaccine is associated with lower risk of dementia. Nature Medicine, 30(10), 2777–2781. https://doi.org/10.1038/s41591-024-03201-5
- Taquet, M., Todd, J. A., & Harrison, P. J. (2025). Lower risk of dementia with AS01-adjuvanted vaccination against shingles and respiratory syncytial virus infections. npj Vaccines, 10, 130. https://doi.org/10.1038/s41541-025-01172-3
- Xie, M., Eyting, M., Bommer, C., Ahmed, H., & Geldsetzer, P. (2025). The effect of shingles vaccination at different stages of the dementia disease course. Cell, 188(25), 7049–7064.e20. https://doi.org/10.1016/j.cell.2025.11.007
- Lophatananon, A., Carr, M., McMillan, B., Dobson, C., Itzhaki, R., Parisi, R., Ashcroft, D. M., & Muir, K. R. (2023). The association of herpes zoster and influenza vaccinations with the risk of developing dementia: A population-based cohort study within the UK Clinical Practice Research Datalink. BMC Public Health, 23(1), 1903. https://doi.org/10.1186/s12889-023-16768-4
- Pomirchy, M., Chung, S., Bommer, C., Strobel, S., & Geldsetzer, P. (2026). Herpes zoster vaccination and incident dementia in Canada: An analysis of natural experiments. The Lancet Neurology, 25(2), 170–180. https://doi.org/10.1016/S1474-4422(25)00455-7