Parkinson’s disease (PD) is characterized by progressive neurodegeneration in the autonomic and central nervous systems, manifesting with hallmark symptoms of resting tremor, bradykinesia and rigidity. The etiology of PD remains elusive, and currently available treatments do not halt disease progression. In this study, conducted within a national health provider, we examined the impact of vaccination and medication purchase on PD occurrence and severity, using an innovative machine learning algorithm to track disease progression. Our findings reveal a significant reduction in PD occurrence following anti-tetanus vaccination, with a time-dependent association between the elapsed time since vaccination and both the rate and progression of PD. These results are supported by evidence that antimicrobial treatments significantly alter disease severity, suggesting the actual involvement of Clostridium Tetani in PD pathology. Thus, tetanus vaccination and C. tetani eradication could be promising strategies for preventing PD and slowing its progression, pending controlled clinical trials. ### Competing Interest Statement The authors have declared no competing interest. ### Funding Statement Funding: This study was funded internally by Leumit Health Services. ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: The Institutional Review Board (IRB) of Leumit Health Services gave ethical approval for this work (LEU-0001-24), with a waiver of informed consent, since data were analyzed retrospectively and anonymously. I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable. Yes Access to patients data is limited to researchers approved by the Institutional Review Board.