Shingles vaccine may cut dementia risk by about 20%

A course of the shingles vaccine may reduce the risk of dementia by about 20%. For a simple intervention with almost no toil, tears or sweat, that is a huge benefit — and one of the most exciting scientific findings in recent years.

Few conditions inspire as much dread as dementia, with Alzheimer’s as its most common cause. The fear stems largely from its insidious nature, robbing people of their identity and leaving loved ones to care for a stranger. The late novelist Sir Terry Pratchett, who had a rare form of the disease, wrote: “Alzheimer’s is me unwinding, losing trust in myself, a butt of my own jokes and, on bad days, capable of playing hunt the slipper by myself, and losing. I felt totally alone, with the world receding from me in every direction.”

Dementia outlook is brighter than feared

The dread also persists because many believe dementia is becoming far more common and will inevitably strike them or those closest to them. Some epidemiologists seem to fuel those fears. Models predict the number of dementia sufferers may triple to 153m by 2050 as societies age.

In reality, the outlook is brighter, especially in rich countries where, adjusted for age, the risk of dementia has dropped sharply in recent decades. Most models assume these declines will not continue, or will even reverse. A mountain of new evidence shows that need not be.

Recent studies highlight the many ways people are already reducing their dementia risk. Many are lifestyle changes you know you should make, such as eating healthily, exercising more and keeping your brain active. Others are medical interventions, like treating hearing loss, depression, high blood pressure and high cholesterol.

But getting people to adopt, and stick to, healthy habits is hard. It does not help that, ideally, you should be working out more and boozing less for many years before your brain will thank you.

How the shingles vaccine may protect the brain

Exactly why this happens is still being debated. One theory is that the varicella-zoster virus, which causes both shingles and chickenpox, contributes to dementia by causing damage or inflammation to the nervous system even while it is supposedly dormant. Another is that the vaccination gives the immune system a firm kick up its B-cells, activating it against other bugs that might contribute to dementia.

Rationing the vaccine makes little sense

Too many public-health systems fail to offer the vaccine to more than just a small share of those who would benefit. Several studies have shown that, taking into account only the shingles cases prevented, it would be cost-effective to vaccinate almost everyone from about the age of 55. Yet many countries have rationed the vaccine to keep down the upfront costs.

Britain, for instance, lowered the eligibility age from 70 to 65 in 2023, but has since been too slow to vaccinate those who were already in their late 60s. Among the 27 members of the European Union, just 17 recommend the vaccine at all, and several reserve it for the over-65s.

That makes little sense when considering only its efficacy against shingles, which afflicts 20-30% of unvaccinated people. It makes even less sense given its potential as a weapon in the fight against dementia.

What health authorities should do next

Most of the evidence of its anti-dementia effect relates to an earlier version of the vaccine, which used a weakened form of the live virus. It has since been largely replaced by a new one, Shingrix, which contains just a sprinkling of proteins from the virus and is seen as safer because it cannot cause an infection.

Some studies suggest the new jab may be at least as powerful against dementia as the old one. Even so, it would make sense to run randomised trials to learn which is better, the optimal age for getting it and whether boosters are needed.

In the meantime, health authorities should not wait. A full two-dose course of Shingrix costs Britain’s health service £320 ($430) and federal immunisation programmes in America around $270: a bargain, given the potential savings in long-term care costs. As for individuals, even the retail cost (around £460 in Britain) is a small price to reduce by one-fifth the chances of having the world recede in every direction.

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