Evidence still not strong enough to say shingles vaccine reduces risk of dementia, says Hiqa

Shingles vaccination may be linked with a lower incidence of dementia, based on available studies. Fewer dementia cases were reported among people with a history of shingles vaccination and among groups eligible for vaccination compared with those who were not. The evidence shows association rather than causation, so it cannot prove that vaccination alone reduces dementia risk. Other adult vaccines, including influenza, have also been linked with lower dementia risk, but they likewise cannot be shown to be the direct cause. Shingles is caused by the varicella-zoster virus and typically involves pain followed by a rash and itchy blisters. Some studies report shingles increases dementia risk, while others find no clear link. Calls exist to make the shingles vaccine free for certain groups such as people over 65 or those who are immunocompromised.

"The available studies reported fewer cases of dementia in people with a history of shingles vaccination, or in groups who were eligible for vaccination, compared with those who were not. "While these studies can show a link, they cannot prove that shingles vaccination reduces dementia risk," Hiqa said."

""Many reviews showed that other adult vaccines, including influenza, are also linked with a lower risk of dementia. Again, they cannot prove that vaccination alone resulted in lower risk." The review identified three considerations to help understand how shingles vaccination might be associated with a lower risk of dementia."

"Shingles, also known as herpes zoster, is an infection of a nerve and the skin around it. It's caused by the varicella-zoster virus, which also causes chickenpox. The main symptom of shingles is pain, followed by a rash that develops into itchy blisters."

"The review identified three considerations to help understand how shingles vaccination might be associated with a lower risk of dementia. These included the link between shingles and dementia, between shingles vaccination and dementia, and between adult vaccination generally and dementia. Hiqa's 's review found that some studies reported that shingles increases the risk of dementia, while others reported no clear link."

Read at Irish Independent