The risk of stroke is significantly reduced for up to two months after receiving a flu vaccine, according to a new study.

The research by the University of Lincoln, funded by the National Institute of Health Research, showed the chances of having a first stroke fell by around a fifth in the first 59 days after receiving the flu jab.

Vaccines administered earlier in the flu season offered greater protection. In the first week after the jab, there were 36% fewer cases of stroke than would be expected among a baseline population, while the second week showed a 30% reduction. The third and fourth weeks saw 24 percent fewer stroke cases, dropping to 17% 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,” says researcher Niro Siriwardena, a GP and professor of primary and pre-hospital health care.

“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.”

It is thought that some cardiovascular diseases may be triggered by flu and that the vaccine could therefore also protect against these conditions, which include stroke.

Siriwardena adds: “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.”