Having the seasonal vaccination against influenza could reduce the risk of stroke in the same flu season by 24%, researchers have found.

An Influenza jab (pictured above) is said to reduce the chances of having a stroke. Photo: U.S Army Corps of Engineers Europe District (via Flickr)Research was conducted at the University of Lincoln and the University of Nottingham.

These findings, reported in the scientific journal Vaccine, indicate a similar link to that found in 2010, when the same research team showed a link between a flu vaccination and the reduced risk of a heart attack.

Lead investigator Professor Niro Siriwardena, Professor of Primary and Pre-hospital Healthcare in the School of Health and Social Care at the University of Lincoln, said:

“The causes of stroke are not fully understood. Classical risk factors like age, smoking and high blood pressure can account for just over half of all cases.”

“We know that cardiovascular diseases tend to hit during winter and that the risks may be heightened by respiratory infections such as flu. Our study showed a highly significant association between flu vaccination and reduced risk of stroke within the same flu season.”

The study, titled IPVASTIA, used a matched case-control design, where actual cases of stroke (the ‘cases’) were compared against ‘control’ patients, adjusted for other factors that might explain the differences in risk associated with flu vaccination such as age, existing diseases and treatment history.

Project statistician Zahid Asghar (also of the University of Lincoln) and Dr Carol Coupland (University of Nottingham) analysed the record of more than 47,000 patients who had suffered a stroke or transient ischaemic attack (or “mini-stroke”) between 2001 and 2009.

They found that flu vaccinations could reduce the risk of stroke by almost a quarter, in particular if the vaccination was given early into the flu season.

“Further experimental studies would be needed to better understand the relationship between flu vaccination and stroke risk,” Professor Siriwardena said.

“However, these findings reinforce the value of the UK’s national flu vaccination programme with reduced risk of stroke appearing to be an added health benefit.”

The study by Professor Siriwardena features on the new website www.FocusOnStroke.nihr.ac.uk, a site which aims to give the public an insight into the NHS’s work in tackling stroke.