Association Between Respiratory Vaccines and Risk of Cognitive Impairment, Dementia and Alzheimer's Disease: A Scoping Review.

Background/Objectives: Neurocognitive disorders represent a growing burden among older adults. Although respiratory vaccines have demonstrated efficacy and safety in preventing acute respiratory events, their potential impact on the development of chronic neurocognitive disorders, such as cognitive impairment, dementia, and Alzheimer's disease (AD), has not been extensively explored. The objective of this scoping review was to synthesize and analyze the available evidence on the association between respiratory vaccination and the risk of developing cognitive impairment, dementia, and Alzheimer's disease. Methods: A scoping review was conducted in accordance with the PRISMA-ScR guidelines. A literature search was performed in the PubMed, Scopus, and Web of Science databases through 15 June 2026. Studies involving older adults (≥60 years), irrespective of their baseline neurocognitive status, were included. Observational studies (cohort and case-control studies) were considered. Editorials, narrative reviews, and other non-original articles were excluded. Results: Eighteen studies were included, with cohort studies being the predominant design. Four main categories of respiratory vaccines were evaluated: influenza, COVID-19, respiratory syncytial virus (RSV), and pneumococcal vaccines, in relation to the risk of cognitive impairment, dementia, and AD. Influenza vaccination was associated with a lower risk of dementia and AD, with a potential dose-response relationship observed, whereby a greater number of vaccinations was associated with a greater reduction in risk. Pneumococcal vaccination was also associated with a lower risk of dementia and AD, particularly among individuals who received a greater number of vaccine doses. In contrast, the evidence regarding COVID-19 and RSV vaccines was limited and yielded heterogeneous findings. Conclusions: Influenza and pneumococcal vaccination maybe associated with a lower risk of Alzheimer's disease and dementia. However, the evidence regarding COVID-19 and RSV vaccines remains limited, and additional studies are needed to clarify their impact on the risk of developing neurocognitive disorders.