Vaccines Against Dementia? New Evidence Reveals Stunning Protection!

For decades, drug companies poured billions of dollars into anti-amyloid Alzheimer research. They were incredibly successful at creating drugs to lower this sticky brain peptide. But dramatically reducing amyloid plaque buildup in the brains of patients with dementia does not seem to reverse decline. A new study in the journal Cell (December 11, 2025) reveals that an old shingles vaccine (Zostavax) not only prevents or delays a diagnosis of dementia, it may also “reduce disease progression among those living with dementia.” Such results are extraordinary.

Anti-Amyloid Dominates Center Stage:

While most of the Alzheimer disease funding was devoted to amyloid research, a small group of investigators was beginning to explore the idea that amyloid buildup in the brain was a reaction to infection. In other words, amyloid could be part of the body’s immune reaction to pathogen invasion. It might be initially trying to protect the brain, but eventually runs amok and causes harm.

We have written extensively about a handful of scientists who began asking whether viruses might be culprits contributing to cognitive decline. In particular they were concerned about herpes viruses such as varicella-zoster (the virus that causes chickenpox and shingles) and herpes simplex type 1 (the virus that causes cold sores). They were asking an unpopular question:

Are viruses (or other pathogens) lighting the match that eventually burns the brain down?

Most neuroscientists ignored that question. It was far easier to hop on the anti-amyloid bandwagon. That’s where the money was. And the FDA went along. It approved three anti-amyloid medications. You can read our analyses of that decision at these links:

“YIKES! FDA Approves Lecanemab Against Alzheimer’s” 

Another Huge Anti-Amyloid Drug Failure Against Alzheimer’s! 

“Herpes Hypothesis? Antiviral Herpes Drugs vs. Alzheimer Disease?” 

Show 1451: Rethinking Dementia: Is What We Believed about Alzheimer’s Wrong? 

New Research Strengthens the Story of Vaccines vs. Dementia:

 Shingles Vaccine May Actually Slow Dementia Progression—Even After Diagnosis

When we first reported on the connection between shingles vaccines and dementia prevention, the news was already exciting. Now there’s even better news: the shingles vaccine might help people who already have dementia.

The study published this week in the journal Cell (December 11, 2025) suggests that the herpes zoster (shingles) vaccine doesn’t just reduce the risk of developing dementia—it may actually slow down the disease once someone has it. According to the research, people with dementia who received the shingles vaccine were almost 30 percent less likely to die from dementia over a nine-year period.

The Researchers Describe Their Results:

“We found that live-attenuated HZ [herpes zoster] vaccination [Zostavax] reduced both new diagnoses of MCI [mild cognitive impairment] among those without any record of cognitive impairment and deaths due to dementia among patients living with dementia. The HZ vaccine thus appears to have a beneficial effect at both ends of the clinical disease course of dementia.

“Our findings suggest that HZ vaccination could be an effective intervention to prevent or delay MCI and dementia, as well as to reduce disease progression among those living with dementia. Such a beneficial effect also appears to exist among those who already have more advanced dementia, based on our finding that the reductions in deaths due to dementia from HZ vaccination tended to be larger among those with more versus less severe dementia.”

Building On Prior Studies That Explored the Role of Vaccines Against Dementia:

The latest research builds on groundbreaking studies we’ve been following closely. Earlier this year, research published in Nature (April 2, 2025) and JAMA (April 23, 2025) revealed that the shingles vaccine reduced dementia diagnoses by 20 percent over seven years.

We were so intrigued that we interviewed the lead scientist, Dr. Pascal Geldsetzer of Stanford University Medicine, on our nationally syndicated radio show. You can listen to our original interview with him at this link:

Show 1394: Viruses, Vaccines and Alzheimer Disease 

The original studies took advantage of what scientists call “natural experiments.” In Wales, people born before September 2, 1933 were never eligible for the free shingles vaccine, while those born on or after that date were eligible. In Australia, a similar cutoff occurred at age 80 when the country launched its shingles vaccination program in November 2016.

These natural experiments are powerful because they compare people who are virtually identical except for their vaccination status. It’s about as close as researchers can get to a randomized controlled trial without actually running one.

Why the New Study in Cell is So Intriguing:

The new Cell article has grabbed headlines because it examined what happens earlier in the disease process and what happens to people already diagnosed with dementia. The idea that an older, not super effective shingles vaccine could both prevent the disease and make a difference even after someone is diagnosed is impressive. If one of the anti-amyloid drugs did both of those things, drug companies would be jumping for joy and charging an arm and a leg for such treatment.

Even more remarkable, among people already living with dementia, those who had received the shingles vaccine had fewer deaths due to dementia. This suggests the vaccine may be slowing the progression of an already established disease.

Two Vaccines Against Dementia: Zostavax vs. Shingrix

The most recent research was based on the older shingles shot, Zostavax. It is no longer available. The newer shingles vaccine is called Shingrix and requires 2 shots. No vaccine is perfect, but Shingrix is substantially more effective at warding off a shingles attack than Zostavax.

A study published in Clinical Infectious Diseases, Feb. 13, 2021 reports that the older live attenuated vaccine [Zostavax]:

“…only offered approximately 50% protection against HZ [herpes zoster or shingles.]

Recombinant zoster vaccine (Shingrix):

“…demonstrated a 97.2% reduction in HZ among adults aged 50 and older.”

Will the newer Shingrix vaccine perform better against dementia than the older Zostavax? No one can say for sure. We might hope that the newer vaccine, Shingrix, would be more effective against dementia, since it is more effective against the virus that causes chicken pox. Because there will never be a head-to-head trial, the answer is unlikely to be revealed. But if you continue to read you will discover some data that look favorable for Shingrix.

The Loudest Shouters Bet on Anti-Amyloid Drugs:

The neuroscience community is a kind of old boys’ network. Once these researchers latched onto amyloid plaque as the cause of Alzheimer disease (AD), they were mostly unwilling to consider other possibilities. We interviewed a key player in uncovering this mess on our radio show # 1416:

“Exposing Fraud and Arrogance in Alzheimer’s Research” 

This podcast is worth a listen because we interviewed Dr. Matthew Schrag, a neurologist who has challenged researchers who helped advance the amyloid plaque theory of AD. We also talked with Charles Piller, author of an essay in the New York Times titled “The Devastating Legacy of Lies in Alzheimer’s Science.” His book, Doctored: Fraud, Arrogance and Tragedy in the Quest to Cure Alzheimer’s, features Dr. Schrag and describes the way the neuroscience community created the amyloid plaque story that has been hard to budge.

The Overlooked Herpes Theory of Dementia:

There is no doubt that amyloid plaque accumulates in the brains of many patients with Alzheimer disease. But what triggers that amyloid accumulation? Could viruses be one of the pebbles that starts a mountain slide that leads to an avalanche we call dementia?

Viral infections cause a lot of mischief! One need look no further than COVID-19 to verify that there can be long-lasting complications after such illnesses. The neuroscience community has long ignored the idea that viruses might play an important role in the development of dementia.

Over 40 years ago, a pathologist named Melvyn J. Ball, MD, linked herpes simplex virus (HSV) type 1 to Alzheimer dementia. Dr. Ruth Itzhaki of the University of Manchester in England has also been studying the relationship between herpes viruses and Alzheimer disease since the early 1990s. Both of these creative thinkers were mostly ignored by the neuroscience community.

A VERY Short History of Vaccines:

Vaccinations are one of the great advances in modern medicine. Diseases like smallpox, polio, diphtheria, measles, whooping cough, influenza and tetanus used to kill hundreds of millions of people around the world.

People who survived their infection might be disabled for life. Polio victims sometimes needed leg braces or wheelchairs to get around. Those who survived smallpox were often left with disfiguring scars or blindness.

Nowadays, most of these dangerous diseases are preventable with vaccinations. Other infections, however, may have lasting consequences that scientists are just starting to recognize.

Infections That Can Cause Long-Lasting Complications:

Lyme Disease:

The bacterium Borrelia burgdorferi can cause chronic Lyme symptoms, even when an infection is treated with antibiotics. Symptoms may include fatigue, brain fog, body aches and heart damage.

ME/CFS (Myalgic Encephalomyelitis/Chronic Fatigue Syndrome):

The cause of ME/CFS remains somewhat mysterious. People often complain of a flu-like illness. It may be caused by an enterovirus. Symptoms can include extreme exhaustion, brain fog, body aches, headaches, joint pain, GI problems and so much more.

Bartonellosis:

The Bartonella bacteria can cause cat scratch fever, trench fever and many long-lasting symptoms. This germ is spread by fleas, sand flies and body lice, to name just a few of the vectors. Veterinarians are especially vulnerable to bartonellosis because so many pets have fleas. Long-lasting symptoms of the disease include relapsing fever, eye problems, foot pain, anemia, fatigue, arthritis and brain fog, to name just a few.

Long COVID:

COVID-19 is the most recent example of an infection resulting in residual symptoms. An estimated 18 million Americans now suffer from long-lasting post-COVID conditions. Those include chronic fatigue, cardiovascular complications, neurological symptoms, brain fog and diabetes.

There are many other infectious agents that can also cause chronic symptoms. They include the polio virus, Epstein Barr virus, West Nile virus, dengue virus and many more viruses and bacteria. The old idea of one and done is long gone. Perhaps you noted that “brain fog” is a common complaint of patients who experience one of these infections.

Infections That Can Cause Long-Lasting Mischief:

Gum disease (periodontitis) is an infection of the tissues around the teeth. It has been linked to heart attacks, heart disease and strokes (Frontiers in Cardiovascular Medicine, Feb. 27, 2023).

Hard-to-treat adult-onset asthma may also be related to infection. Chlamydia pneumoniae causes sore throats, sinus infections, laryngitis and bronchitis in its acute phase. Symptoms sometimes last for several weeks.

According to the CDC, C. pneumoniae infections might also raise the risk of a person developing arthritis or atherosclerosis as well as asthma. These conditions may not show up until after the infection appears to be long gone.

Should You Worry About the Flu?

A lot of people think of influenza as little more worrisome than the common cold. Now evidence from the Netherlands shows a clear link between flu infections and heart attacks (NEJM Evidence, July 2024).

Heart attacks were six times more likely to occur during the week after suffering an episode of the flu. There is evidence that vaccinating against influenza can also protect people from major adverse cardiovascular events (European Heart Journal Suppl., Feb. 14, 2023).

A New/Old Vision of Dementia:

Let me offer you a metaphor that might, or might not, be a fair representation of the origins of Alzheimer disease. Imagine a match being lit in a broom closet of a large house. If that match falls on a pile of rags, it might slowly start a smoldering fire. Over time, that fire could burn out of control. There would be a lot of smoke and eventually it would burn the house down.

Someone watching from outside might first see the smoke. Eventually that person would detect flames. Finally, the fire would become fully apparent and eventually the whole house would be demolished.

What if one of the metaphorical matches of Alzheimer’s disease is a viral infection? Trying to put out the fire by sucking up the smoke would be fruitless. The only way to prevent the brain from burning down would be to either prevent the match from lighting in the first place or putting out the fire before it could take hold.

Tens of billions of dollars have been spent creating and developing medications that eliminate beta amyloid plaque in the brain. If that sticky protein is equivalent to smoke from the fire, eliminating it would do little, if anything, to prevent the “burning” brain from continuing its downward spiral.

If, on the other hand, viruses are the matches, then vaccinating against the resulting sparks or treating with anti-viral medications might actually slow or stop the brain fire from progressing.

Could a Shingles Shot Vaccine Help Against Dementia?

Vaccines may play a key role in preventing dementia. There is growing evidence that herpes viruses could be contributing to the development of Alzheimer disease (Journal of Alzheimer’s Disease, Feb. 13, 2024).

Several vaccine shots have shown potential to reduce the likelihood of developing dementia. They include flu shots (NPJ Vaccines, March 2, 2024) and BCG vaccine used to prevent tuberculosis or treat bladder cancer (Journal of Alzheimer’s Disease, March 19, 2024). BCG stands for Bacillus Calmette-Guérin. It is a 100-year-old vaccine that was originally developed to fight TB.

Even more exciting, research suggests that people who get vaccinated against shingles (herpes zoster) lower their risk for dementia (Brain and Behavior, Feb. 2024).

This meta-analysis of five studies involving over 100,000 patients concluded:

“Our data demonstrated that patients who had herpes zoster vaccination were at a significantly lower risk of developing dementia.”

More Proof That We Could Use Vaccines Against Dementia:

A study last year in Nature Medicine (July 25, 2024) was titled:

“The recombinant shingles vaccine is associated with lower risk of dementia”

What is a recombinant shingles vaccine? It is Shingrix from GSK. It contains glycoprotein E (gE) from the chicken pox (varicella-zoster) virus. The vaccine is over 90% effective at preventing an attack of shingles.

The investigators compared Shingrix (FDA approved in 2017) to an older shingles vaccine (Zostavax) that was approved in 2006.

People who received the more effective shingles shot:

“…were at a lower risk of dementia in the next 6 years…translating into 17% more time lived diagnosis-free, or 164 additional diagnosis-free days among those affected.”

That isn’t to say the older Zostavax vaccine was ineffective, though. The meta-analysis of five studies described above (Brain and Behavior, Feb. 2024) concluded that all shingles vaccinations are associated with a lower risk of dementia.

It also appears that all vaccinations may reduce the risk of developing dementia. That is the conclusion of an article published in the Journal of Alzheimer’s Disease (Sep. 12, 2023):

“The Impact of Routine Vaccinations on Alzheimer’s Disease Risk in Persons 65 Years and Older”

The investigators reviewed 16 million medical records from an insurance claims database. About 1.6 million senior citizens were followed for more than eight years. Those who were vaccinated for tetanus and diphtheria were 30% less likely to receive a diagnosis of Alzheimer disease. Shingles vaccinations (herpes zoster or HZ shots) lowered the risk by 25%. Pneumonia vaccines also reduced the likelihood of developing dementia by about 27%.

For our sophisticated readers, these were relative risk reductions. Absolute risk dropped by 2 to 3 percent.

The authors concluded:

“Using a retrospective cohort study, we found that there were significant decreases in AD for patients 65 and older who received a Tdap/Td [tetanus and diphtheria] vaccination (30%), an HZ [herpes zoster] vaccination (25%), or a pneumococcal vaccination (27%) versus separate unvaccinated groups over an 8-year period. Our main analysis results are consistent with other studies of these three vaccines suggesting a possible preventative effect on dementia.”

The Shingrix vaccine actually produced better results. People who received at least one dose of this shingles vaccine reduced their likelihood of developing Alzheimer disease by 73%.

How Could a Shingles Shot Protect Against Dementia?

When a child catches chicken pox from the varicella zoster virus (VZV), the pathogen doesn’t disappear. Instead, the virus goes into hibernation in nerve cells (ganglia) around the spinal cord and brain. It can hang out for many decades without seeming to cause any mischief.

If the virus becomes reactivated, however, it can cause a whole lot of hurt. For one thing, shingles can be extremely painful. The rash literally hurts like hell. Sometimes the pain lingers for months or years because of lasting nerve damage.

My Interpretation of What Is Going On:

The virus that causes shingles, varicella zoster, “wakes up” after lying dormant for decades inside our nerve cells. The authors of the study in Wales and Australia suggest that reactivation of the varicella zoster (shingles) virus may have a secondary impact and reactivate dormant herpes simplex virus (HSV-1). So, you get a double whammy of herpes virus activation: zoster and HSV-1.

When such viruses are reactivated, they cause a lot of damage. “Neuroinflammation” in the brain can harm blood vessels and cause lots of other mischief, including the buildup of amyloid plaque and nerve damage. This chain of events could ultimately lead to memory loss and many of the other clinical manifestations of dementia.

I want to emphasize that this is a “plausible mechanistic pathway.” It is yet to be proven. But it would explain why herpes viruses like varicella zoster and HSV-1 could trigger a cascade of events that ultimately lead to cognitive dysfunction. If this turns out to be supported by future research, it bolsters the idea of using vaccines against dementia. Antiviral drugs such as valacyclovir might also be helpful.

Final Words:

The idea that viruses may contribute to neurological disorders is controversial. However, if vaccines could prevent or delay the development of dementia (or heart attacks), they might revolutionize our approaches to hard-to-combat cardiovascular and neurological conditions.

There is a growing anti-vax movement in the United States. That alarms me. I am not objective about this issue. That’s because I had polio as a child before there were polio vaccines. I also caught whooping cough long before there was a pertussis vaccine. Both diseases could have been fatal.

I still suffer from PTSD because of my days in a polio ward as a child. Children were dying all around me. Being restrained in traction when you are a little kid is a life-altering situation.

I am not advocating that everyone rush out and get a shingles shot. But I would hope that the anti-vax movement will not discourage people from considering the unexpected health benefits of such vaccinations.

Final-Final Words:

If you found our interpretation of the articles in Cell (December 11, 2025), JAMA (April 23, 2025) and Nature (April 2, 2025) of interest, why not listen to our interview with the senior author? We spoke with Pascal Geldsetzer, MD, of Stanford University Medicine about his research when the preprint was first published. We also spoke with Bodil Weidung, PhD, of Uppsala University, Sweden. Both investigators have been involved in research indicating that herpes viruses could play an important role in the pathogenesis of Alzheimer’s disease. They describe the nature of their different studies and why neuroscientists need to start thinking creatively about ways to overcome dementia.

Here is a link to Show 1394:

“Viruses, Vaccines and Alzheimer Disease”

You can listen to the audio stream by clicking on the white arrow inside the green circle under the photo. Or you can download the mp3 file by scrolling to the bottom of the page under the “Listen to the Podcast” heading.

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