Could a shingles vaccine, which is now available in South Africa, also fight dementia? The evidence appears to be positive, writes Linda Nordling for Bhekisisa.
This time last year, Cape Town’s Melanie Verwoerd felt a pain like nothing she’d experienced before. A 20cm-wide band of angry blisters, stretching across her back and under her arm all the way to her stomach, kept the former MP and South African ambassador to Ireland out of action for months. “I’ve had many operations and a lot of pain in my life, but never something like that,” she says.
The rash was shingles, the disease caused by the chickenpox (varicella-zoster) virus that around a third of us will experience at least once in our lifetime.
Determined to stop a recurrence at any cost, Verwoerd asked her GP about Shingrix, the new shingles jab she’d heard about that besides preventing the condition, might also lower the chances of developing dementia by up to a quarter.
But it was not yet available in South Africa.
Shingrix finally launched in the country at the end of June, almost a decade after it was approved in the United States, at the eye-watering price of R2 783 per injection, according to GlaxoSmithKline (GSK). And you need two shots, taken two to six months apart.
That’s a steep price for a country with little appetite for adult vaccination (only about a third of adults take the flu shot and less than 4% took the previous shingles jab that was available here).
So will the lure of a sharper mind in old age be enough to change that calculus?
Filling a care gap
Almost anyone who has had chickenpox can get shingles, as the virus hides in the nervous system for life. The risk climbs with age and with anything that weakens the immune system. Most cases clear up within weeks, but for some, the pain lingers long after the rash heals – a condition called post-herpetic neuralgia that can last months or, in severe cases, years.
South Africa lived with an older, considerably less effective shingles vaccine from 2011 until 2024: Zostavax was a live vaccine, meaning it contained a weakened version of the shingles virus as its active ingredient. Therefore, it could not be given to people with a weak immune system, who might otherwise catch the disease the vaccine was designed to prevent.
This, for instance, included people on chemotherapy or on treatment for autoimmune diseases like lupus or diabetes, as well as people with HIV, who all have a higher chance of developing shingles. HIV-positive people, even those successfully on HIV treatment, have a three-to-five-fold higher risk of shingles compared with the general population.
Another problem with Zostavax was its relatively low efficacy – it prevented shingles only in 64% of people aged 60-69, which dropped sharply with age to 18% in the over-80s, in whom a bout of shingles can quickly lead to serious health problems.
“You can be robust and (shingles) spits you out frail,” India Butler, a geriatrician at Wits Donald Gordon Medical Centre in Johannesburg told Bhekisisa. “It’s terrible.”
By contrast, Shingrix, which is more than 90% effective in over-50s, stays highly effective in older groups, too. “It’s a brilliant, amazing vaccine,” says Butler.
The anti-dementia effect
But preventing shingles may not be Shingrix’s only draw. Since news broke in July 2024 that Shingrix may protect against dementia, it has sparked intense debate. In the US, it led to patients asking neurologists about using shingles jabs as a tool to prevent it, while in Ireland, experts used the evidence to advocate for adding the shingles vaccine to its adult vaccination programme.
Verwoerd, who ended up travelling overseas to get the vaccine, told Bhekisisa that anti-dementia claims findings had made her keen on Shingrix even before she got shingles. “I think it should be free,” she says. If the dementia claim holds true, she adds, vaccinating older adults against shingles seems like a bargain compared with the cost of dementia care.
However, Ina-Mari McAlister, a GP at Bergvliet Family Practice in Cape Town, says none of her patients has asked about Shingrix based on the dementia claims so far. “I expect the greatest interest will be from older adults and from people who have already experienced shingles, especially those who have had more than one episode,” she said.
She puts this indifference down to a lack of knowledge about the dementia findings. “I don’t think many people are aware of it,” she said.
So what are the facts?
As it turns out, both Zostavax and Shingrix appear to be associated with some level of protection against dementia, according to data from countries such as the United Kingdom and the United States that rolled out the vaccines to large numbers of people.
Allison Glass, a clinical virologist who heads the molecular pathology department at Lancet Laboratories in Johannesburg, says it’s plausible.
Shingles can cause vasculitis – swelling of the blood vessels – in the brain, which can lead to small blockages that don’t register as overt strokes, she says. “I can imagine how that could lead to dementia over time. It makes sense to me that that could be a factor.”
One study exploited an arbitrary birth-date cut-off in Wales’ Zostavax roll-out that meant people born just days apart had very different chances of getting vaccinated. That created two otherwise similar groups, where the group that got the jab had about a 20% lower risk of developing dementia over the next seven years than the one that didn’t.
That helped researchers tell whether the vaccine, rather than something else, caused the difference they saw.
Another study took a different approach, using America’s switch from Zostavax to Shingrix in 2017 to compare the two vaccines’ effects on dementia. People who received Shingrix on average took five months longer to develop dementia than similar people who received the older shingles vaccine.
Other studies have also linked shingles vaccines to slower ageing, fewer strokes and heart attacks and a lower chance of dying.
But none of the studies to date is enough to conclusively say that the vaccine is the cause of these beneficial side effects. The gold standard for doing that would be a double-blind, randomised controlled trial, in which one group of participants get the vaccine and the other a dummy jab. Researchers then compare the results of the two groups over time.
A matter of risk
In addition to the question of proof, there’s an important caveat to note when talking about the size of the effect. A 24% reduction in dementia risk – as one study by Shingrix maker GSK found over three years of follow-up – equates to about two fewer dementia cases per 1 000 people over three years.
That small reduction could nevertheless have big effects across a population, especially taking into account the high cost of caring for people with dementia. And dementia cases in South Africa are forecast to almost triple by 2050, as people live longer and as conditions that raise dementia risk, diabetes and hypertension among them, become more common.
Will such considerations play into discussions in South Africa about the roll-out of Shingrix?
Discussions around whether Shingrix will be subsidised by medical aids will “be guided by clinical evidence, regulatory requirements and affordability”, Noluthando Nematswerani, Discovery Health’s chief clinical officer, said in a statement to Bhekisisa.
As for a public sector roll-out, this will depend on a recommendation from the national advisory group on immunisation, which the Health Department told Bhekisisa it hasn’t yet received.
GSK says it is “open to relevant discussions” with the government, but no tender exists, and no timeline has been set.
One challenge for these discussions is that shingles is not a notifiable disease in South Africa, so there are no precise data on how big the health problem it actually is.
“Certainly, with our large immunosuppressed population, we’ve got even more of a burden than most of most other countries,” says Glass. “But there’re no data on what that incidence is, because nobody records that.”
South Africa’s low take-up of adult vaccines could also count against a wider roll-out.
While vaccine hesitancy plays a part, it’s also a consequence of how the health system is structured, says Butler. “We lurch from crisis to crisis, and preventative medicine opportunities are often lost because we’re so busy putting out fires.”
The flu vaccine, Butler points out, carries a strikingly similar list of associated health benefits to Shingrix: lower dementia risk, reduced all-cause mortality and fewer complications from frailty, to name just a few. And it’s free, covered by the state and by most medical aids, she says.
“And do you think we can get people to take the bloody flu vaccine?”
Bhekisisa article – What if a shingles jab could also protect your brain? (Creative Commons Licence)
See more from MedicalBrief archives:
Another study throws light on shingles vaccine effect in dementia fight
Shingles jab may cut heart attack, stroke risk – global review
RSV and shingles jabs tied to lower dementia risk – Oxford analysis
Shingles jab may help ward off dementia – UK study