Older adults who received the Shingrix shingles vaccine were 24% less likely to be diagnosed with dementia over four years in a study of more than 500,000 people. Researchers estimate the difference could amount to roughly one dementia case prevented for every 17 people vaccinated.
That’s why you have to read it further than the headline. They would tell you if it’s just correlation or if they proved causation.
In this case, they state down at the end that this does not prove causation and also that they received funding from glaxo smith kline
It’s not just Shingrex. All vaccines show protection. Viral infections produce a lot of reactive oxygen from the innate immune response. In younger people, that ROS is cleared by mitochondria but as people age, mitochondria get less efficient. So less infections = less chance of neuronal damage.
But from a UK study, only women saw the protective effect of shingrex.