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Tetanus vaccine may reduce risk of Parkinson’s disease

A new study reveals a significant reduction in Parkinson’s disease occurrence after getting a tetanus vaccine, with a time-dependent association between the elapsed time since vaccination and the rate and progression of Parkinson’s disease. This is a preliminary study, so we shouldn’t assume that the tetanus vaccine will prevent Parkinson’s disease, but it is intriguing.

The tetanus vaccine, as a part of the Tdap vaccine for tetanus, diphtheria, and pertussis, is recommended for adults every 10 years, but that’s to prevent tetanus, nothing else. Since tetanus can cause a painful tightening of all of your muscles, which leads to a medical emergency to prevent death, getting the vaccine is an important prevention strategy for adults and children.

This new study may provide more unintended benefits of the tetanus vaccine. As I usually do, I will present data from that study and see what it tells us about the vaccine and the risk of Parkinson’s disease.

close up photo of a person pouring mixture on a tube Parkinson's disease tetanus vaccine
Photo by Artem Podrez on

What is Parkinson’s disease?

Parkinson’s disease (PD) is a form of movement disorder that happens when nerve cells do not produce enough of a chemical in the brain called dopamine. The cause is unknown, although it may be genetic or exposure to chemicals in the environment.

Symptoms begin gradually, often starting on one side of the body and eventually affecting both sides. These symptoms include:

  • Trembling of hands, arms, legs, jaw and face 
  • Stiffness of the arms, legs and trunk 
  • Slowness of movement 
  • Poor balance and coordination 

As symptoms get worse, people with the disease may have trouble walking, talking, or doing simple tasks. They may also have problems such as depression, sleep problems, or trouble chewing, swallowing, or speaking.

There is no specific test for PD, so it can be difficult to diagnose. Doctors use a medical history and a neurological examination to diagnose it.

Tetanus vaccine and Parkinson’s disease research

In a paper posted on 21 May 2024 in the pre-print server medRxiv, Ariel Israel, MD, Ph.D., Leumit Research Institute, Tel-Aviv, Israel, and colleagues developed a large-scale observational study in Leumit Health Services in Israel selected 1,446 patients who received a Parkinson’s disease diagnosis between the ages of 45 and 75.

The key finding of this study was that 1.6% of those with PD had received the tetanus vaccine before their diagnosis, compared with 3.2% of those without. That translates to a 50% reduction in the risk of Parkinson’s disease in the group that received the tetanus vaccine.

Within two years of the last tetanus vaccination, there was a 0% risk of developing Parkinson’s disease. Within five years of the last vaccination, there was an 83% reduction in the risk of developing PD. There was a 74% reduction in risk if the vaccine was given between five and ten years prior. After 15 years post-vaccination, there was no statistical difference in the risk of PD between the vaccinated and unvaccinated groups.

Why might this be happening? The authors speculated that:

These results are supported by evidence that antimicrobial treatments significantly alter disease severity, suggesting the actual involvement of Clostridium tetani (the bacterial that causes tetanus) in PD pathology.

In other words, the bacteria that causes tetanus may be linked to Parkinson’s disease, and the vaccine, which prevents the infection, may have the unintended benefit of reducing the risk of PD.

close up view of person holding a vaccine
Photo by Karolina Kaboompics on


I want to ensure everyone understands that this study was not peer-reviewed and was published on a preprint server. This means that we should view these results cautiously until they are published in a major journal after peer review.

That being said, there has been some evidence that Clostridium tetani bacteria in the gut may be linked to PD. Therefore, if we can prevent the infection by the bacteria, we can reduce the risk of Parkinson’s disease.

This is another case of “more research is necessary” before we make broad claims that the tetanus vaccine can prevent Parkinson’s disease. But this data is intriguing and may solidify the importance of the vaccine for long-term health.


Michael Simpson
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