So is this because of reduction of inflammation? Inquiring minds want to know.
http://www.lincoln.ac.uk/news/2014/02/848.asp
Having the seasonal flu jab could reduce the risk of suffering a stroke by almost a quarter, researchers have found.
Academics
from the University of Lincoln and The University of Nottingham in the
UK discovered that patients who had been vaccinated against influenza
were 24% less likely to suffer a stroke in the same flu season.
Their findings are reported in the scientific journal Vaccine.
In 2010, the same research team showed a similar link between flu vaccination and reduced risk of heart attack.
Lead
investigator Professor Niro Siriwardena, who is Professor of Primary
and Pre-hospital Healthcare in the School of Health and Social Care at
the University of Lincoln and also a GP and Research Lead with
Lincolnshire Community Health Services NHS Trust, 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 results were consistent with our previous research into
heart attack risk."
Dr Zahid Asghar, statistician on the project,
supported by Dr Carol Coupland (University of Nottingham) analysed
records of more than 47,000 patients who had suffered a stroke or TIA
(transient ischaemic attack, or "mini stroke") between 2001 and 2009.
Data were drawn from the UK's national General Practice Research
Database (now the Clinical Practice Research Datalink). Alongside flu
vaccine take-up, they also looked at take-up of pneumococcal
vaccination, which protects against infections like pneumonia.
They
found flu vaccination was associated with a 24% reduction in risk of
stroke. The reduction was strongest if the vaccination was given early
in the flu season. There was no statistically significant change in risk
of TIA with flu vaccination. Pneumococcal vaccination did not appear to
reduce risks of either stroke or TIA.
The study, called
IPVASTIA, used a matched case-control design. Actual cases of stroke
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. This
type of analysis is widely used in health research to identify risk
factors in large samples, although it cannot prove direct
cause-and-effect relationships.
Professor Siriwardena added:
"Further experimental studies would be needed to better understand the
relationship between flu vaccination and stroke risk. 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."
In the UK the seasonal flu vaccination is recommended
for everyone over 65 years of age and other at-risk groups, such as
those with disabilities or chronic illnesses. Take-up of the vaccine
across England is lower than national targets at 74% for over-65s in
2011/12 and around 52% for under-65s in at-risk groups.
The study by Professor Siriwardena and his co-researchers features on a new website, www.FocusOnStroke.nihr.ac.uk,
launched today (20th February 2014) by the UK’s National Institute for
Health Research. The site aims to give the public an insight into the
great work being done in the NHS to tackle stroke.
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