Shingles vaccine could keep dementia at bay
The NHS shingles vaccine delays the onset of dementia by up to nine months, research by Oxford University suggests.
The Shingrix jab is currently offered to everyone aged 70 to 79 as well as those with a weakened immune system, and is being gradually rolled out to the over-65s.
As well as fighting shingles, a study has now shown that it also seems to delay a dementia diagnosis by an average of five to nine months, which could have a major impact on rates of the disease in Britain.
Oxford University is not sure what is driving the effect, but says it is possible that the herpes zoster virus that causes shingles may also trigger dementia.
John Todd, professor of precision medicine at the University of Oxford’s Nuffield Department of Medicine, said: “By inhibiting the virus, the vaccine could reduce this risk.
“Alternatively, the vaccine also contains chemicals, which might have separate beneficial effects on brain health.”
Shingles is caused by a reactivation of the chickenpox (herpes zoster) virus, which lies dormant after an infection and causes weeks of painful blisters, headaches, fever and, in severe cases, death.
It is particularly dangerous for the elderly, which is why they are offered a vaccine by the NHS.
Researchers were able to conduct a natural experiment into the unexpected benefits of the GSK Shingrix vaccine after the US switched from using Merck’s shingles jab Zostavax, in 2017.
Several small studies had already suggested that Zostavax might reduce the risk of dementia so researchers seized the opportunity to find out what would happen once the jab was altered.
The team followed 200,000 people aged 65 and over for six years, and discovered that Shingrix was even more effective at staving off dementia than the previous vaccine.
Although the number of people eventually diagnosed with dementia remained the same, they had enjoyed an extra 164 dementia-free days on average – equating to 17 per cent more time without the condition compared with people on Zostavax.
When compared with people taking other jabs, such as the flu or tetanus vaccine, the effect was even greater, with 27 per cent more time spent without dementia – equating to around nine months.
The current uptake of the Shingrix vaccine is around 60 per cent, and Oxford researchers said it was high enough that a fall in dementia rates in Britain may start to be noticeable in the coming years, linked to the roll-out.
‘This will be a good test’
Dr Maxime Taquet, National Institutes of Health Research clinical lecturer at the University of Oxford, said: “The mean age was just over 70 in both groups and so I think if the expectation is that if this is a causal effect, then we would see a reduction in dementia in the UK once people started taking up the shingles vaccines for the team. This will be a good test of this hypothesis.”
There are estimated to be 944,000 people with dementia in Britain, with the majority suffering from Alzheimer’s.
The number is expected to increase to more than one million by 2030, with one in three people born in the UK this year expected to develop dementia in their lifetime.
The condition costs the country ￡34.7 billion annually and is now the leading cause of death, but current drugs can only help symptoms, not put the brakes on progression.
Researchers at Oxford believe that the vaccine may work even better if given earlier and say data should be available within the next few years to find the “sweet spot” for delivery.
Paul Harrison, a professor of psychiatry at the University of Oxford, said: “Dementia is a major and increasing problem, and it’s perhaps the disease people fear most in old age, but the reality is we still can’t do very much to prevent the inexorable progression or even delay its onset.
“It will be interesting to see if when people hear of these findings, whether the public choose to increase the uptake of the shingles vaccine when they’re offered by the NHS
“There should be enough people within not too long that we’ll be able to get a handle on whether any beneficial effect is indeed age-related. And in which case, is there a sweet spot or when the vaccine might have its greatest benefits against dementia risk.”
The findings were welcomed by experts from other universities and charities, who called for further studies to validate the research.
Andrew Doig, professor of biochemistry at the University of Manchester, said: “A link between infection with the herpes zoster virus and the onset of dementia has been suspected for some time.
“Now, we need to run a clinical trial of the recombinant vaccine, comparing patients who receive the vaccine with those who get a placebo. We also need to see how many years the effect might last and whether we should vaccinate people at a younger age.
“We know that the path to Alzheimer’s disease can start decades before any symptoms are apparent, so the vaccine might be even more effective if given to people in their 40s or 50s.”
Dr Sheona Scales, director of research at Alzheimer’s Research UK, said: “Dementia isn’t an inevitable part of ageing; it’s caused by diseases like Alzheimer’s. So finding new ways to reduce people’s risk of developing these diseases is vital.
“It isn’t clear how the vaccine might be reducing risk, nor whether the vaccine causes a reduction in dementia risk directly, or whether there’s another factor at play. So it will be critical to study this apparent effect further.”
The study was published in the journal Nature Medicine.
