Could the Shingrix or Zostavax Vaccine Help Prevent Dementia?

More than 7 million Americans are suffering with Alzheimer disease (AD). The Alzheimer’s Association reports that 1 out of 9 senior citizens will develop some degree of dementia. By 2060 as many as 14 million Americans will have AD (Alzheimer’s & Dementia, April 29, 2025). What if a vax against shingles such as the Shingrix or Zostavax vaccine could help prevent dementia?

Changing Direction is Challenging:

For decades, Alzheimer’s research has focused on one prime suspect: amyloid plaques in the brain. Drug companies have spent billions developing medications to clear away those sticky protein fragments. The drugs are amazingly effective at lowering amyloid levels. Unfortunately, most patients still experience little improvement in memory or thinking ability. That disappointing reality has forced scientists to ask a provocative question: What if amyloid isn’t the real cause of Alzheimer disease? 

A growing number of researchers now suspect that infections and the brain’s immune response may play an important role. And one of the most intriguing clues comes from an unexpected source, an older shingles shot known as the Zostavax vaccine.

A Surprising Discovery About the Zostavax Vaccine

The shingles virus can remain hidden in the body for decades.

Anyone who had chickenpox as a child carries the virus that causes shingles: varicella zoster. Even after the rash disappears, the virus retreats into nerve tissue near the brain and spinal cord.

Decades later it can reactivate, causing shingles. But shingles may do more than trigger a painful rash. Some researchers believe that viral reactivation could contribute to inflammation and blood vessel damage in the brain, potentially increasing the risk of dementia.

That hypothesis gained credibility after several large studies examined what happened to people who received the Zostavax vaccine, an earlier shingles vaccine.

The Zostavax Vaccine Natural Experiment in Wales

One of the most intriguing studies emerged from Wales after the government introduced the Zostavax vaccine in 2013.

Eligibility depended on birth date. People born on or after September 2, 1933 could receive the vaccine. Those who had already turned 80 were not eligible.

That seemingly arbitrary cutoff created a perfect natural experiment. People just a few months apart in age are remarkably similar. The main difference was whether they could receive the Zostavax vaccine.

Researchers analyzed detailed health records and found something remarkable: People who received the Zostavax vaccine were about 20 percent less likely to develop dementia over the next seven years (Nature, April 2, 2025).

Watch Our Interview on the Zostavax Vaccine and Dementia

We recently spoke with Pascal Geldsetzer, MD, PhD, MPH, a Stanford physician-scientist whose research helped uncover this surprising connection between shingles vaccination and dementia risk.

Dr. Geldsetzer has analyzed natural experiments in Wales, Australia and Ontario, Canada, and the results have been remarkably consistent.

In this fascinating conversation, he explains:

• how a bureaucratic quirk created a powerful research opportunity
  • why viral infections might influence Alzheimer disease
  • and why a simple vaccine could potentially reduce dementia risk

His ideas challenge long-held assumptions about Alzheimer disease and open the door to entirely new prevention strategies.

https://www.youtube.com/watch?v=71YDIgIBcF8 

Zostavax Vaccine Results Replicated in Other Countries

The Welsh findings were so intriguing that researchers looked for similar opportunities elsewhere. They found them. Australia introduced a shingles vaccination program for adults aged 70 to 79, but people who had already turned 80 were excluded.

That policy created another natural experiment involving the Zostavax vaccine. The results were strikingly similar. People who received the vaccine were significantly less likely to be diagnosed with dementia in the following years (JAMA, June 17, 2025). 23, 2025).

A similar pattern was later observed in Ontario, Canada (Lancet Neurology, Feb. 2026). When multiple natural experiments in different countries produce comparable results, researchers begin to take notice.

Why Might the Zostavax Vaccine Influence Dementia Risk?

At first glance, the connection between shingles vaccination and dementia sounds improbable. But there are plausible explanations.

When the varicella zoster virus reactivates, it can cause inflammation in the brain and damage small blood vessels. Researchers suspect that this process may trigger a cascade of events that eventually leads to cognitive decline.

Shingles outbreaks may also reactivate other herpes viruses. A Swedish study found that people infected with herpes simplex, the virus responsible for cold sores, were twice as likely to develop dementia over the following 15 years (Journal of Alzheimer’s Disease, Feb. 13, 2024).

The infection-connection theory of AD is not new. More than 40 years ago, pathologist Melvyn J. Ball, MD proposed that herpes viruses might help trigger Alzheimer disease (Canadian Journal of Neurological Sciences, Aug. 1982). Why neuroscience has mostly ignored Dr. Ball’s research is a mystery to us.

The Zostavax Vaccine Is Gone, But Its Successor May Be Even Better

The studies described above relied on the Zostavax vaccine, which is no longer used in the United States. It has been replaced by a newer vaccine called Shingrix.

The Shingrix vaccine is substantially more effective at preventing shingles:

• 97 percent effectivein adults 50 to 69
  • 91 percent effective in adults over 70

Protection also appears to last longer than with the older Zostavax vaccine.

Because Shingrix stimulates a stronger immune response, researchers are now wondering whether it might provide even greater protection against dementia.

New Research on the Shingrix Vaccine and Dementia

Recent data suggest that is a possibility. A study of Kaiser Permanente patients compared people who received the Shingrix vaccine with those who did not.

The vaccinated group had a 51 percent lower risk of developing dementia (Nature Communications, Feb. 9, 2026).

Other research suggests shingles vaccination may benefit the heart as well.

A massive study of more than one million adults in South Korea found that people who received a shingles vaccine were 25 percent less likely to experience major cardiovascular events, including heart attacks, strokes and heart failure (European Heart Journal, May 5, 2025).

Why Preventing Shingles Matters in Its Own Right

Even without the dementia question, shingles prevention can be enormously valuable. Shingles causes a painful rash, but the suffering often continues long after the rash fades. The complication is called postherpetic neuralgia (PHN)—persistent nerve pain that can last months or even years.

One reader shared her father’s experience:

“I would encourage anyone on the fence about getting the Shingrix vaccine to seriously consider it. My elderly father had the older shingles vaccine but not Shingrix. Several years ago, he had shingles so badly that he was hospitalized twice because the pain was uncontrollable.

“Due to the shingles, he now has post-herpetic neuralgia (PHN). Although he takes morphine and gabapentin, the daily pain of PHN is almost unbearable. It is so bad he often cries out loud.

“His pain management doctor has prescribed other drugs and performed a nerve block, but nothing has helped. He went from being an active man prior to shingles (bowling, volunteering, splitting firewood by hand) to someone who is housebound because of post herpetic neuralgia.”

Another reader described her own ordeal:

“I have had shingles on the top of my head, my forehead and inside my eye. It burns with constant, sharp, knife-like pain that goes down through my head and behind my eye. I can’t sleep.”

Depending upon age and immune system function, two doses of the Shingrix vaccine are about 86 percent effective at preventing postherpetic neuralgia, one of the most dreaded complications of shingles.

Can You Get Shingles More Than Once Even Without the Zostavax Vaccine?

Yes. People who have had shingles once can experience another outbreak later in life. For that reason, the CDC recommends that all adults over 50 receive two doses of the Shingrix vaccine, even if they have already had shingles.

People who previously received the Zostavax vaccine can also benefit from the newer Shingrix vaccination.

One Rare but Serious Side Effect of the Shingrix Vaccine

No medical treatment is completely free of risk. In 2021 the FDA required the manufacturer of Shingrix to update prescribing information after researchers detected a small increase in Guillain-Barré syndrome (GBS) following vaccination.

The additional risk was estimated at about six cases per million vaccinations within the first six weeks (FDA Safety Communication, March 24. 2021).

For most people, the benefits of vaccination appear to far outweigh this relatively small risk.

Could the Zostavax Vaccine Discovery Change Alzheimer Prevention?

As mentioned, more than seven million Americans already live with Alzheimer disease. Current Alzheimer drugs that target amyloid plaques are extremely expensive and offer limited clinical benefit.

A vaccine is comparatively inexpensive. If preventing viral reactivation reduces dementia risk, even modestly, the public health impact could be substantial.

The Zostavax vaccine studies may have opened the door to a radically different way of thinking about Alzheimer disease. Instead of treating dementia after brain damage occurs, future strategies might focus on preventing viral triggers decades earlier. And that could change the trajectory of Alzheimer disease for millions of people.

Final Words:

Neuroscientists are also looking at other strategies. A mouse study in Science Translational Medicine (Feb. 11, 2026) found that an old medicine for epilepsy (levetiracetam) may prevent buildup of toxic proteins in the brain.

One reader shared her husband’s experience:

“My husband was prescribed levetiracetam (known commercially as Keppra) about two months before he died. He’d had Alzheimer’s for at least 10 years and couldn’t talk or walk by then. He experienced cognitive improvement noticed by his care staff as well as the hospice nurse and doctor. It included restoration of some verbal ability and awareness of his surroundings.

“I wish we had started this treatment sooner. I found out later that studies on this drug go back at least a decade. None of the drugs doctors usually prescribe for AD work, and they have serious side effects. How different would our lives have been if my husband had been started on this one much sooner?”

One personal story is not proof that this treatment would work for anyone else. More research is needed to determine if the old and inexpensive anti-seizure drug levetiracetam will be helpful for other people with AD. In the meantime, though, it looks as if researchers are beginning to consider a variety of new strategies that may prove more successful than the current amyloid-depleting drugs.

Did you find this article and our video interview with Dr. Geldsetzer of interest? If you did not take time to watch, here is the link again:

https://www.youtube.com/watch?v=71YDIgIBcF8

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