New research suggests that the flu shot reduces the risk of suffering a stroke.

Researchers from the University of Lincoln found that chances of having a first stroke fell by around a fifth in the first 59 days after receiving the flu jab.

In the first week after the jab, there were 36 per cent fewer cases of stroke than would be otherwise expected among a 'baseline' population, while the second week showed a 30 percent reduction. The third and fourth weeks saw 24 percent fewer stroke cases, dropping to 17 percent between 29 days and 59 days after the jab.

"This is a significant finding, and if confirmed in a clinical trial could be one that can change lives," researcher Niro Siriwardena said in a statement.

For the study, researcher used a method known as a self-controlled case series to assess how having the flu vaccine affected by the risk of stroke over time in almost 18,000 cases. Each case involved a patient aged 18 or older who had suffered a first stroke between 2001 and 2009, with just over half the cases being women. They compared how many strokes occurred up to 180 days after exposure to the effects of the flu vaccine with other times when the person would not have been protected by the vaccine.

"Our findings support current recommendations for the flu vaccination in people at high risk, but with the added effect of stroke prevention. Our study demonstrated that the earlier the vaccination is delivered the greater the linked reduction in stroke risk, so this should also encourage early vaccination," Siriwardena said. "We are now at the point of developing further studies into whether it could be recommended to extend vaccination to younger adults at risk of stroke. If a causative link between influenza vaccination and reduction in stroke risk is confirmed by experimental studies and if this leads to higher vaccinations rates, there would be significant benefits for patient and population health."

This latest study builds on previous results which linked the flu vaccine to a reduction in risk of stroke -- as well as a reduced risk of suffering a first heart attack. 

The findings are detailed in the journal Vaccine.