Influenza vaccination is associated with a reduced Alzheimer’s disease (AD) risk among older adults, according to a study published in the Journal of Alzheimer’s Disease. Avram S. Bukhbinder, MD, and colleagues used deidentified claims data to compare the risk for incident AD between patients (aged 65 and older) with and without prior influenza vaccination (935,887 influenza-vaccinated and influenza-unvaccinated matched pairs). During a median follow-up of 46 months, 5.1% of the vaccinated patients and 8.5% of the patients developed AD. The relative risk was 0.60 and the absolute risk reduction was 0.034, corresponding to a number needed to treat of 29.4. “Since there is evidence that several vaccines may protect from AD, we are thinking that it isn’t a specific effect of the flu vaccine,” the study authors wrote. “Instead, we believe that the immune system is complex, and some alterations, such as pneumonia, may activate it in a way that makes AD worse. But other things that activate the immune system may do so in a different way—one that protects from AD.
