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Clinical Summary

Do Common Vaccines Reduce the Risk of Dementia?


  • The use of common vaccines was not associated with a lower risk of dementia in adults aged ≥50 years.

Why This Matters

  • Findings do not support the role of immunisations in the prevention of neurodegenerative disease.

Study Design

  • Findings are from a population-based cohort study that included 13,383,431 participants (age ≥50 years) without dementia using data from the UK Clinical Practice Research Datalink (1988-2018).
  • Funding: A Research Grant from the Benter Foundation to Dr Brassard.

Key Results

  • During 140,721,533 person-years of follow-up, 443,484 participants were diagnosed with dementia, with corresponding crude incidence rate of 3.2 per 1000 person-years.
  • Exposure to common vaccines was associated with a higher risk of dementia (adjusted OR [aOR] 1.38; 95% CI 1.36 to 1.40).
  • The increased risk was mainly driven by the immunisations for influenza (aOR 1.39; 95% CI 1.37 to 1.41) and pneumococcus (aOR 1.12; 95% CI 1.11 to 1.13).
  • The application of a 10-year lag period (aOR 1.20; 95% CI 1.18 to 1.23) and prostate cancer screening (aOR 1.17; 95% CI 1.09 to 1.25), but not breast cancer screening (OR 1.39; 95% CI 1.31 to 1.47), attenuated the increased risk of dementia.


  • Observational design.
  • Risk of residual confounding.