Objective: Pneumonia is the leading cause of death in patients with dementia. The efficacy of the pneumococcal polysaccharide vaccine 23 (PPV23) in these patients is uncertain. This study aims to analyze the role of the PPV23 on preventing community pneumonia in Alzheimer’s disease and Mixed Dementia patients.

Method: It is a retrospective cohort study. Vaccinated and non-vaccinated patients were compared for the following outcomes: diagnosis, hospitalization and death from pneumonia or all causes. Data on the characteristics of 510 individuals older than 60 years with the diagnosis of Alzheimer's disease or Mixed Dementia were collected at a public outpatient clinic in a city from the South of Brazil, from January 1, 2015 to December 31, 2018.

Results: From 510 individuals, 237 (46.5%) were vaccinated with PPV23 and 74 (14.5%) had all-cause pneumonia. There was no significant association between PPV23 vaccination and the risk of pneumonia or death.

Conclusion: No association between PPV23 and pneumonia or death in dementia patients was found in the studied population. This is the first study with PPV23 exclusively in dementia patients. Future and largest studies should be done to prove the efficacy of this vaccine in this population.