The Effect of Influenza Vaccination on Hospitalization and Mortality Among People With Dementia

Abstract

Introduction: People with dementia have an increased risk for infection-related complications, which may be mitigated by common vaccinations. The aim was to investigate the association between influenza vaccination and the rates of all-cause and influenza-related hospitalizations and deaths among older adults with dementia. Methods: We followed all Danish residents with dementia aged 65 and above from September 1, 2002, to August 31, 2018. Dementia was defined from records in the Danish national registries (positive predictive value 85.8%). People with dementia were identified on September 1 of each year. On this date, vaccination status was also reset, and the status of covariates was assessed. We used proportional hazard Cox regression to compare rates of all-cause hospitalization, hospitalization with a respiratory infection, hospitalization with influenza or pneumonia, and all-cause mortality for vaccinated and unvaccinated. Results: Across the entire study period, we included 134,002 people with dementia. Rates of hospitalization were 9%–10% lower, and the mortality rate 9% lower, for vaccinated compared to unvaccinated among people with dementia. Discussion: Influenza vaccination was associated with lower rates of hospitalization and mortality among people with dementia. Further exploration of the preventive potential of influenza vaccination among people with dementia is important for shaping interventions in this vulnerable group.