ANNUAL influenza (flu) vaccination is associated with a lower risk of stroke, according to a new study by Francisco J. de Abajo, University of Alcalá, Madrid, Spain, and colleagues.
“Studies have shown that getting the flu increases your risk of having a stroke, but research is still being collected on whether getting the flu vaccine can help protect against a stroke,” said de Abajo. Therefore, the researchers started an observational study to determine if those who have the flu vaccine have a lower risk of ischaemic stroke, the most common type.
Delving into a healthcare database in Spain, the researchers selected individuals who were 40 years old or older who had their first stroke over a 14-year period, identifying 14,322 people. Then, every individual was compared with five others of the same age and sex who had not had a stroke (71,610 people). The researchers then determined whether people had had a flu vaccine at least 14 days prior to the stroke and before that date for individuals who had not had a stroke.
While 41.4% of individuals who had received a flu vaccine also had a stroke, compared with 40.5% of those who did not have a stroke, this is because the people receiving the vaccination were more likely to be older. The older the individual, the more likely they are to have other conditions that can contribute to a stroke, such as high blood pressure and high cholesterol. Once these factors were adjusted, the researchers found that individuals who had a flu vaccine were 12% less likely to have a stroke than those who were not vaccinated.
As the study was an observational one, there is no definitive proof that a flu vaccination does reduce the risk of stroke. It merely shows an association; however, de Abajo believes that this is enough of a reason for individuals to have their flu vaccination. “These results are yet another reason for people to get their yearly flu shot, especially if they are at an increased risk of stroke. To be able to reduce your risk of stroke by taking such a simple action is very compelling,” said de Abajo.
The researchers also investigated whether the pneumonia vaccine had a similar association; however, no protective effect was found.