P.066 The protective effect of influenza vaccination against stroke in adults

Abstract

Background: Respiratory infection can be an immediate precursor to stroke and myocardial infarction (MI). Influenza vaccination is associated with reduced risk of MI. This relationship has also been suggested for stroke although it is unclear if the effect is consistent across age and risk groups. Methods: Using administrative data in Alberta from September 2009 – December 2018 we modelled the hazard of any stroke for individuals recently exposed (< 182 days) to the influenza vaccine compared to those without recent exposure adjusted for age, sex, anticoagulant use, atrial fibrillation, COPD, diabetes, hypertension, income quintile, and rural/urban home location. Results: 4,141,209 adults (29,687,899 person-years) were included; 1,769,565 (43%) received at least one vaccination in the 10-year time span. 38,126 stroke events were recorded. Adjusted for demographics and comorbidities, recent influenza vaccination significantly reduced the hazard of stroke (HR: 0.77; 95% CI: 0.76 – 0.79). This effect persisted across all stroke subtypes and across all ages and risk profiles. Conclusions: There is a 23% reduction in hazard of stroke among those recently vaccinated against influenza compared to those who were not. Protection extended to the entire adult population and was not limited to high-risk groups only.