Objectives: Influenza, which is a virus-induced acute infectious disease, spreads rapidly and widely and may incur complications. Vaccination is regarded as the most effective defense against influenza because studies have shown that influenza vaccination effectively reduces the likelihood of complications and death. However, studies have not been conducted on older adults with dementia, who are disadvantageous in terms of health conditions and medical accessibility. Due to population aging and a rapid increase in the dementia population, this study examined the effectiveness of influenza vaccination on older adults with dementia.
Methods: An observational study was conducted on adults aged 65 years or higher who were diagnosed with dementia. Special needs files from the 2010–2012 National Health Insurance Research Database were referenced. Logistic and multiple regression analyses were performed on the influenza-vaccinated and non-vaccinated participants regarding their likelihood of contracting influenza and subsequent complications (namely pneumonia and influenza, acute and chronic respiratory diseases, acute cerebrovascular diseases, and heart diseases), likelihood of receiving short-term (1–3 months) or long-term (1–9 months) clinical treatment, use of hospitalization, and all-cause mortality.
Results: Overall, this study comprised 114,712 participants, 33.3% of which were administered influenza vaccine. The control variables were age, sex, whether they are low-income households, comorbidity, history of clinical visits of Western medicine in the preceding year, and the use of hospitalization in the preceding year. In comparison with the non-vaccinated participants, the vaccinated participants did not exhibit a decrease in clinical medical usage and costs for influenza and its complications. However, those who had contracted influenza showed a decrease in clinical costs, revealing that the severity of the disease was reduced among these participants. Moreover, the vaccinated participants exhibited significantly lower use and costs of hospitalization and shorter length of hospital stay for short-term and long-term pneumonia, influenza, acute and chronic respiratory diseases, acute cerebrovascular diseases, and heart diseases than the non-vaccinated participants. Compared with the non-vaccinated participants, the vaccinated participants exhibited a significantly lower short-term and long-term all-cause mortality rate (25.4% and 23.5%, respectively).
Conclusion: This study found that administering influenza vaccine to older adults with dementia profoundly reduced their likelihood of hospitalization and risk of death caused by influenza and complications. The government should encourage vaccination in this group of older adults to strengthen their resistance against influenza.