The link between the zoster vaccine and a lower dementia risk has been strengthened in new research.

A study by Stanford Medicine, published in the journal Nature on April 2, found that the vaccine — which is used to prevent shingles — reduced the probability of a new dementia diagnosis by about 20% over the next seven years.

“If these findings are truly causal, the zoster vaccine will be both far more effective and cost-effective in preventing or delaying dementia than existing pharmaceutical interventions,” the researchers noted in the study.

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These findings also support an emerging theory that viruses impacting the nervous system can increase dementia risk.

Senior study author Pascal Geldsetzer, MD, PhD, assistant professor of medicine at Stanford, said he considers these findings “hugely important” for clinical medicine, population health and research.

“For the first time, we now have evidence that likely shows a cause-and-effect relationship between shingles vaccination and dementia prevention,” he told Fox News Digital. 

“We find these protective effects to be large in size – substantially larger than those of existing pharmacological tools for dementia.”

The randomized trial took advantage of the unique way the zoster vaccine was rolled out in Wales, U.K., in 2013, Geldsetzer noted.

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“They said that if you had your 80th birthday just prior to the start date of the program, you are ineligible, and you remain ineligible for life,” he said. “If you had your 80th birthday just after, you were eligible for at least one year.”

“We see in our data that just a one-week difference across this date-of-birth cutoff means that you go from essentially no one getting vaccinated to about half of the population getting vaccinated.”

The study found that women benefited from the vaccine more than men in terms of reduced dementia risk. (iStock)

Both the vaccine-eligible and ineligible groups are “good comparison groups,” according to Geldsetzer, since the only difference is that they were born a few days earlier or later.

The same protective effect of shingles vaccination for dementia has been identified in different populations and countries that rolled out the vaccine in a similar way, the researcher revealed.

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To gather more evidence and confirm the link, Geldsetzer recommends conducting a clinical trial.

“I’m currently trying to raise funds to conduct such a trial from private foundations and philanthropy,” he said.

“We want to trial the live-attenuated vaccine (the vaccine for which we have generated our compelling body of evidence), which is no longer being manufactured in the U.S.”

The protective effect of shingles vaccination for dementia has been identified in different populations and countries, according to researchers. (iStock)

Family physician Dr. Mark Loafman, who was not involved in the study, weighed in on the association between the shingles vaccine and dementia risk.

“We commonly see intriguing headlines from studies showing an association between a particular health outcome and exposure to something in the environment, our diet or medication,” the Chicago doctor said in an interview with Fox News Digital. 

“The challenge when interpreting this type of data is that an association is in no way proof that the exposure is what caused the health finding.”

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Loafman said this large-population study does a “very good job” of excluding the possibility that the vaccinated and unvaccinated groups share different attributes that could skew the outcome.

“So, it really does look like the vaccine does indeed offer a fairly significant level of protection against developing dementia.”

These findings support an “emerging theory” that viruses impacting the nervous system can increase dementia risk, according to Stanford Medicine. (iStock)

“The study also includes compelling evidence to support two highly plausible mechanisms … in which the vaccine decreases the incidence of dementia,” he added.

This includes the fact that the herpes virus, which causes chickenpox and shingles, settles into the nervous system and lies dormant, which can ignite shingles later. 

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“Secondly, the live-attenuated vaccines, like the shingles vaccine, are associated with neuroprotective properties,” Loafman went on. “The association is not in itself causal, but this study adds a lot more credibility to this association.” 

Loafman, who has already received the shingles vaccine himself, said he will recommend it to patients in light of this research.

“These findings bring even more encouragement for me to recommend it to my eligible patients, friends and family,” he said.

Newer and more expensive medications are more likely to be made in the United States or Europe. Ireland, in particular, has become a hub because it is a tax haven.

Many of the industry’s biggest blockbusters are manufactured at least partly in Ireland. Among them are: Keytruda, Merck’s cancer drug; Zepbound, Eli Lilly’s weight-loss drug; and Stelara, Johnson & Johnson’s anti-inflammatory drug used for conditions like arthritis.

Mr. Trump has taken notice. “This beautiful island of five million people has got the entire U.S. pharmaceutical industry in its grasp,” he said in March at a meeting with Prime Minister Micheal Martin of Ireland.

Why did U.S. drug manufacturing move overseas?

U.S. production of pharmaceuticals peaked, by one measure, in 2006.

That was around the time a wave of top-selling American-made drugs lost patent protection, creating opportunities for generic manufacturers in India and China to ramp up production of generics. Around the same time, U.S. government incentives to manufacture in Puerto Rico were phased out, while new carrots, like tax advantages in Ireland, encouraged manufacturers to move production overseas.

In 2021, most of America’s top-consumed generic drugs, as well as key antibiotics and antivirals, had no American facility producing their active ingredients, according to Clarivate.

Mr. Trump said on Wednesday that “the United States can no longer produce enough antibiotics to treat our sick.”

For example, nearly all the world’s sites producing the active ingredient of amoxicillin, a common antibiotic, are in China, India or Europe, according to Clarivate.

A Tennessee plant, now owned by a company called USAntibiotics, used to supply nearly all of the amoxicillin consumed in the United States. It now imports the active ingredient from Europe and uses it to formulate pills. The plant now supplies about 5 percent of America’s amoxicillin.

Have drugs been subject to tariffs before?

Medications are usually protected from tariffs under a World Trade Organization agreement aimed at protecting patients’ access to vital drugs. The tariffs that Mr. Trump imposed on certain imports in his first term did not hit pharmaceuticals.

Starting in February, drugmakers importing active ingredients made in China into the United States have had to pay a tariff that Mr. Trump imposed on Chinese goods. That tariff rose to 20 percent in March. (Wednesday’s levies add a new 34 percent tariff on most Chinese imports, though that does not apply to medicines.)

Will tariffs lead to drug shortages?

For the manufacturers of inexpensive generic drugs with razor-thin profit margins, the added costs of tariffs could be “a tipping point” that prompts them to exit the market, said Erin Fox, an expert at the University of Utah who tracks drug shortages.

Dr. Fox said she was most worried about drugs for which shortages are already common, such as generic medications given as an injection. These injections are harder to make than pills and are much less profitable than newer medications, discouraging manufacturers from jumping in. An example is lidocaine, used to numb pain during medical procedures. Most production of lidocaine’s active ingredient is in India, according to Clarivate.