Forbes has a strange but true example of unintended (but welcome) consequences. It seems like Shingrix, the new shingles vaccine, also offers protection against developing dementia:
The scientists studied health outcomes of more than 200,000 people who received one of the two different shingles vaccines and found that the recombinant shingles vaccine, Shingrix, reduces dementia by at least 17% more than the older, but now discontinued, live shingles vaccine, Zostavax. Further, they found that Shingrix reduced dementia risk by 23-27% than did vaccines against other illnesses. This equates to 5-9 months or more dementia-free days of life.
This protective effect was seen in both sexes, but was greater in women.
Interestingly, after the live vaccine against shingles, Zostavax, was introduced in 2006, several studies suggested it might reduce the risk of dementia. Later, Zostavax was discontinued in many countries, including the USA and UK, in favor of the much more effective vaccine, Shingrix.
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It was during this switchover between the two vaccine types that participants were identified for this comparative study. This provided the rare opportunity to compare the risk of dementia in the six years following Shingrix compared to the otherwise similar group of people who received Zostavax. There were more than 100,000 people in each group. The study also compared Shingrix to vaccines against other infections (flu and tetanus, diphtheria, and pertussis).
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How might Shingrix protect against dementia?
“One possibility is that infection with the Herpes zoster virus might increase the risk of dementia, and therefore by inhibiting the virus, the vaccine could reduce this risk, replied co-author, John Todd, a Professor of Precision Medicine at the University of Oxford and Director of the Wellcome Centre for Human Genetics and of the JDRF/Wellcome Diabetes and Inflammation Laboratory (DIL).
“Alternatively, the vaccine also contains chemicals which might have separate beneficial effects on brain health,” Dr Todd added. These chemicals, known as adjuvants, are designed to ensure that your immune system reacts strongly to the vaccine so a lasting immune response develops.
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You can read more of the Oxford research here, in Nature Medicine.