Having the flu jab could also help prevent strokes, a new study by UK researchers has suggested.
The study by the University of Lincoln found the chances of having a first stroke were significantly reduced for up to two months after getting the flu vaccine.
The findings, published in the journal Vaccine, support the idea that some cardiovascular diseases may be triggered by flu and that the vaccine could help protect people against conditions including stroke.
“Our findings support current recommendations for the flu vaccination in people at high risk, with the added effect of stroke prevention”
Protection provided by the vaccine against flu lasts from four to six months.
The study, which was funded by the National Institute of Health Research, was based on an analysis of 18,000 stroke cases between 2001 and 2009.
The research team compared how many strokes occurred up to 180 days – about six months - after a flu jab with other times when people would not have been protected by the vaccine.
They found the chances of having a stroke dropped by about a fifth in the first 59 days after getting the jab.
Meanwhile vaccinating earlier in the flu season appeared to offer more protection against stroke. In the first week after the jab there were 36% fewer cases of stroke than would normally be expected.
The second week showed a 30% reduction. That was 24% in the third and fourth weeks, dropping to 17% between 29 and 59 days after the jab.
“Our findings support current recommendations for the flu vaccination in people at high risk with the added effect of stroke prevention,” said one of the three-strong research team Niro Siriwardena, a GP and professor of primary and pre-hospital healthcare.
“Our study demonstrated that the earlier the vaccination is delivered the greater the linked reduction in stroke risk so this should encourage early vaccination,” he said.
He said the team were developing further studies to look at benefits of extending flu vaccination to younger adults at risk of stroke.