The study was published November 1 in The Lancet Public Health.
The study sample consisted of 4 141 209 adults (29 687 899 person-years of observation time) registered under the provincial health-care system between Sept 30, 2009, and Dec 31, 2018 (of Alberta, Canada). 1 769 565 (42,73%) individuals received at least one vaccination during the study period, and 38 126 stroke events were recorded. Adjusted for demographics and comorbidities, recent influenza vaccination significantly reduced the hazard of stroke (hazard ratio 0,78 [95% CI 0,76–0,79]). This association persisted across all stroke types.
Influenza vaccination is associated with a reduced risk of stroke among adults, even if they aren't at high risk for stroke, according to new research. The risk of stroke was about 23% lower in the 6 months following a flu shot, regardless of the patient's age, sex, or underlying health conditions.