‘More than just flu prevention’
In an accompanying editorial, Dixon Yang, MD, and Mitchell S.V. Elkind, MD, agree that the findings point to intriguing potential unexpected benefits of the vaccine.
“This case-control study ... importantly suggests the influenza vaccine is more than just about preventing the flu,” they wrote.
Dr. Elkind said in an interview that the mechanism could indeed involve an anti-inflammatory effect.
“There is some evidence that antibiotics also have anti-inflammatory properties that might reduce risk of stroke or the brain damage from a stroke,” he noted. “So, it is plausible that some of the effect of the vaccine on reducing risk of stroke may be through a reduction in inflammation.”
Dr. Elkind noted that the magnitude of the reduction observed with the vaccine, though not substantial, is important. “The magnitude of effect for any one individual may be modest, but it is in the ballpark of the effect of other commonly used approaches to stroke prevention, such as taking an aspirin a day, which reduces risk of stroke by about 20%. But because influenza is so common, the impact of even a small effect for an individual can have a large impact at the population level. So, the results are of public health significance.”
The study received support from the Biomedical Research Foundation of the Prince of Asturias University Hospital and the Institute of Health Carlos III in Madrid. Dr. Elkind has reported receiving ancillary funding but no personal compensation from Roche for a federally funded trial of stroke prevention.
A version of this article first appeared on Medscape.com.