Stroke and myocardial infarction can both be directly preceded by a respiratory illness. According to a study in The Lancet Public Health, people who receive an influenza vaccination experience a lower risk of stroke compared to the unvaccinated.

The research team analyzed incidences of acute ischemic stroke, intracerebral haemorrhage, subarachnoid haemorrhage, and transient ischemic attack in 4.1 million persons who participated in the study. The risk of stroke occurrences was then examined among people who had had a flu vaccination in the preceding six months or not.

During the study period, 1.8 million people (or 43% of the population) had at least one immunization. Each year they participated in the study, about 97,000 participants received the flu shot, including 29,288 who did so for each of the 10 flu seasons and were included in the study.

Regardless of the patient′s age, sex, or underlying medical issues, a reduction of 23% was observed in the risk of stroke in the six months following a flu shot. Further, the risk of all forms of stroke was significantly reduced, although acute ischemic stroke and intracerebral haemorrhage were the most affected. In addition, influenza vaccination also decreased risk across all age groups and risk categories, except for people without hypertension.

Thus, the study′s results imply that widespread influenza vaccination may be a potentially effective public health measure to lower the incidence of stroke.

(Source: https://www.medscape.com/viewarticle/983953?src=#vp_1)