Editorial 2 : Shingles vaccine & lower dementia risk: what new study says
Context
The shingles vaccine may do more than protect against the viral infection. A recent study from South Korea found that those vaccinated have a 23% lower risk of developing cardiovascular conditions and reduced odds of the onset of dementia, a debilitating neurodegenerative disorder which does not yet have very effective treatments.
What is shingles?
- Shingles is a viral infection that causes painful rashes.
- It can occur anywhere on the body and typically looks like a single stripe of blisters that wraps around the left or right side of the torso, along the path of the nerve from which the virus spreads.
- It is caused by the varicella-zoster virus — the virus which also causes chickenpox.
- After a bout of chickenpox, usually during childhood, the virus remains dormant in one’s nerve cells for life.
- It can reactivate and cause shingles when a person’s immune system is weakened.
- People who have never had chickenpox may get the infection if they come in direct contact with the fluid released by the shingles rashes, or breathe in the virus particles.
- Pain can persist even after rashes go away. In severe cases, the rashes cause vision loss if they are close to the eye, facial paralysis, or inflammation of the brain.
- The shingles vaccine, which prevents the reactivation of the varicella-zoster virus, is recommended primarily to individuals over the age of 50 years.
- It may also be recommended to adults living with a weakened immune system due to conditions such as HIV.
What did the Welsh study find? Why is it unique?
- Previous studies shown an association between shingles vaccination and lower risk of dementia.
- The unique roll-out strategy of the shingles vaccine in Wales created a “natural experiment” that effectively mimicked a randomised control trial, the most credible level of evidence in medical research, much better than patient records.
- Shingles-causing virus has been linked to long-lasting cognitive effects. Preventing its reactivation through vaccination, could directly reduce the risk of dementia.
- Some researchers have also pointed to changes in the immune system brought about by the shingles virus which could protect against dementia.
Shingles vaccines
- There are two approved shingles vaccines — both of which are available in India.
- Zostavax uses a live, weakened virus, while Shingrix uses a recombinant technology to develop parts of the virus that do not cause the disease.
Way forward
In conclusion, accumulating evidence suggests that various common vaccines—including those for shingles, diphtheria, pneumococcal disease, hepatitis A, and typhoid—may be associated with a reduced risk of dementia. These findings highlight the potential of vaccination not only for preventing infectious diseases but also for contributing to long-term cognitive health.