Flu Vaccine Offers Moderate Protection From Stroke

WEDNESDAY, Sept. 7, 2022 (HealthDay News) -- Influenza vaccination seems to have a moderate protective effect on ischemic stroke, according to a study published online Sept. 7 in Neurology.

Sara Rodríguez-Martín, Pharm.D., Ph.D., from the University of Alcalá in Madrid, and colleagues conducted a nested case-control study to examine the association between influenza vaccination and risk for a first ischemic stroke during pre-epidemic, epidemic, and postepidemic periods. The source cohort included individuals aged 40 to 99 years with at least one-year registry and no history of stroke or cancer; five controls were randomly selected per case, matched for exact age, sex, and date of stroke diagnosis (index date; 14,322 incident ischemic stroke cases and 71,610 matched controls).

The researchers found that 41.4 and 40.5 percent of the cases and controls, respectively, were vaccinated, yielding a crude odds ratio of 1.05. Vaccinated individuals had a higher prevalence of vascular risk factors, disease, and comedication; after full adjustment, the association of influenza vaccination with ischemic stroke yielded an adjusted odds ratio of 0.88, which appeared early (adjusted odds ratio_{15 to 30 days}, 0.79) and decreased over time (adjusted odds ratio_{>150 days}, 0.92). The reduced risk was of similar magnitude for noncardioembolic and cardioembolic stroke, in all three epidemic periods and in all subgroups.

"These results are yet another reason for people to get their yearly flu shot, especially if they are at an increased risk of stroke," a coauthor said in a statement. "To be able to reduce your risk of stroke by taking such a simple action is very compelling."

Several authors disclosed financial ties to Sanofi.

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