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Viruses can interact to trigger Alzheimer’s

Viruses can interact to trigger Alzheimer's

Viruses can interact – common viruses, such as Varicella, can trigger the awakening of other viruses, such as those in the Herpes family, which then may cause Alzheimer’s Disease; this is according to a research study by Tuft’s.

Chain reaction between viruses

Almost all of us has had chicken pox; unfortunately, the virus then remains dormant in 95% of us. Age and a declining immune system (caused by age, stress, or immunosuppression) can reawaken this virus (varicella) later in life and people then develop shingles (Varicella Zoster Virus, or VZV).

VZV has been previously linked to Alzheimer’s Disease by causing neuroinflammation, although other studies suggest that VZV alone is not linked to a higher risk of dementia. We have covered research showing that a bout of shingles can be associated with an increased risk of a heart attack or stroke later in life.

Some people are prone to Shingles recurrence.

Tufts University in Medford, Massachusetts researchers have shown (1) that the Varicella can interact with, or reawaken, the Herpes 1 virus, a virus that is normally linked to cold sores, but which usually lies dormant in the nerve cells for decades. Up to 80 percent of American adults are estimated to be carriers of Herpes 1. Unfortunately, Herpes can also be linked to an increased risk of dementia.

Thus there’s a chain reaction effect. Viruses can interact: Varicella reawakens Herpes, which then may cause dementia.

Can Covid vaccines reawaken Varicella?

Unfortunately, ‘catching’ Covid-19, or having one of the mRNA vaccines (Pfizer or Moderna) may also been linked to increased cases of Shingles. In a 2021 study (2), 86.27% of shingles cases appeared after Covid vaccination. The average time after vaccination was 6.92 days. The research was conducted amongst people more likely to have recurrence. In the general population, a study of over one million people given the mRNA Covid vaccine concluded that a higher incidence of Herpes Zoster was statistically detectable post-COVID-19 vaccine (3). The overall ‘feeling’ in several studies is that the reason for the reawakening of Varicella may be due to immunosuppression by the vaccine. 

So Covid-19 vaccines may also be part of the idea that viruses can interact! They may also be part of the chain reaction – the vaccine can reawaken Varicella, which can reawaken Herpes, which can prompt cold sores and dementia.

HSV-1 and Alzheimer’s

In the Tuft’s study researchers found that when VZV becomes activated appearing as shingles, it can in turn reactivate dormant herpes simplex virus type 1, or HSV-1. And a significant amount of research has shown an association between activated HSV-1 and Alzheimer’s.

In the research, Varicella was not seen to cause neuroinflammation on its own, and there was no tau protein tangle and no build up of amyloid plaque. But where there was dormant HSV-1 in the neurons, the Varicella axctivated it, and amyloid plaque and tau proteins grew, with a reduction of eclectic transmission.

Dr Ruth Itzhaki of Oxford University stated that it was becoming increasingly clear that infection, and viruses in particular, played a significant role in Alzheimer’s Disease. Professor David Kaplan, who with Dana Cairns of Tufts, led the study, concluded that researchers should be looking at ways of preventing these viruses taking a hold in humans to prevent diseases such as Alzheimer’s. 

More vaccines are one likely solution.

Chris Woollams, former Oxford University Biochemist, comments, “These findings that viruses can interact, are actually very worrying on a number of fronts. For example, any decrease in the strength of your immune system might prompt this ‘chain reaction’. Can any virus turn another on? We know viruses play a role in other illnesses such as cancer, for example, with Epstein Barr and lymphoma, or breast cancer and HPV and HIV. There are new vaccines on the way to treat all of these viruses. You can be sure of that.

Go to:  Alzheimer’s and Dementia research news



  1. Potential Involvement of Varicella Zoster Virus in Alzheimer’s Disease via Reactivation of Quiescent Herpes Simplex Virus Type 1; Journal of Alzheimer’s Disease, vol. 88, no. 3, pp. 1189-1200, 2022; 25 May 2022.
  2. Can SARS‐CoV‐2 vaccine increase the risk of reactivation of Varicella zoster? A systematic review; Hardik D. Desai et al; J Cosmet Dermatol. 2021 Nov; 20(11): 3350–3361. 
  3. Real-world evidence from over one million COVID-19 vaccinations is consistent with reactivation of the varicella-zoster virus; M Hertel et al; JEADV; 26 April 2022 https://doi.org/10.1111/jdv.18184