Scientists from the University of Oxford (UK) compared the effects of two types of shingles vaccines administered to adults. One of them is the so-called "live" vaccine, which contains weakened microorganisms that can cause an infection but not the disease. These weakened, harmless pathogens multiply in the body, triggering an immune response (this teaches the immune system to recognize and fight the virus). The second vaccine, which researchers have now examined, is the recombinant shingles vaccine, which has replaced the "live" version in many countries.
Recombinant vaccines are created by inserting a fragment of the pathogen’s genetic material into mammalian or yeast cells. These genetically modified (recombinant) cells begin producing a new protein, which, after isolation and purification, becomes the vaccine antigen - explains the Polish vaccination portal Szczepienia.info.
British researchers found evidence that the new recombinant shingles vaccine reduces the risk of dementia. They published their findings in the journal Nature Medicine.
Could a Vaccine Protect Against Dementia?
Shingles is an infectious disease caused by the herpes virus VZV (HHV-3), the same virus responsible for chickenpox. In people who have had chickenpox, the virus remains dormant in the nervous system and can reactivate when the immune system weakens or the person is fatigued, causing shingles (symptoms include rashes, blisters filled with whitish fluid, nerve pain, and fever). It mainly affects older individuals, typically those over 50, which is why the shingles vaccine is offered primarily to seniors.
After the introduction of the "live" shingles vaccine (Zostavax) in 2006, some studies suggested a lower risk of dementia among those who received it, although the results were inconclusive. In recent years, however, Zostavax has been withdrawn in many countries and replaced by the more effective recombinant vaccine Shingrix. Now, a new study conducted on over 200,000 individuals indicates that Shingrix may have additional positive effects.
We demonstrated that the recombinant vaccine is associated with a significantly lower risk of dementia within six years of vaccination. Receiving the vaccine was associated with a 17% increase in dementia-free time, which translates to 164 additional days without the disease for those later affected by it. The recombinant shingles vaccine was also linked to a lower risk of dementia compared to two other vaccines commonly given to older adults: the flu vaccine and the tetanus/diphtheria/pertussis vaccine, the researchers write in their study summary.
In other words, the study group showed at least a 17% reduction in dementia diagnoses within six years of receiving the new shingles vaccine. These positive vaccination effects were observed in both genders, though more significantly in women. The effects of Shingrix were also compared to vaccines for other infections (influenza and tetanus/diphtheria/pertussis), and Shingrix was associated with a lower risk of dementia than both Zostavax and those vaccines.
What Do Experts Say?
The size and nature of this study make the findings compelling and should motivate further research. They support the hypothesis that shingles vaccination may prevent dementia. If confirmed in clinical trials, these results could be highly significant for older individuals, healthcare systems, and public health
- said Dr. Maxime Taquet, a clinical lecturer in the Department of Psychiatry at Oxford and co-author of the study.
The results are intriguing and encouraging. Anything that can reduce the risk of dementia is welcome, given the large and growing number of people affected by the disease
- added Paul Harrison, professor of psychiatry at Molecular Targets.
Experts are also pondering the mechanism by which the shingles vaccine may influence dementia. It’s possible that the chickenpox virus itself can trigger dementia, and weakening the virus could provide some protection. Alternatively, the vaccine may contain chemicals that have beneficial effects on brain health. We don’t know the answer yet.
