The flu jab could offer protection to people with heart conditions or diabetes, research has found.
With the expected H1N1 pandemic and seasonal flu outbreaks this winter, medical researchers claim that anyone with those conditions should be encouraged to have the jab.
The call comes after evidence gathered by the UCL Centre for Infectious Disease Epidemiology, London, UK, and the London School of Hygiene and Tropical Medicine revealed there was a rise in deaths due to heart disease or incidence of heart attacks during times when the influenza virus was circulating. The proportion of excess influenza deaths that were due to heart disease averaged 35 per cent.
The conclusion was reached after researchers conducted a systematic review of the evidence to examine the association between influenza and heart attacks or cardiovascular death, including the possible cardioprotective effects of the influenza vaccine.
The findings, in the October edition of The Lancet Infectious Diseases, analysed 42 papers describing 39 studies between 1932 and 2008.
The study, led by Charlotte Warren-Gash , Andrew C Hayward and Liam Smeeth, looked at a range of observational studies in different settings that reported consistent associations between influenza and heart attacks, but a weaker association with death from heart disease.
Four out of eight observational studies showed a protective effect against heart attacks or cardiovascular events in those vaccinated against influenza. Two, small randomised trials suggested that the influenza vaccination reduced the risks of cardiovascular death and some cardiac events.
But the authors said that despite the availability of the vaccine, only 47.2 per cent of those in the chronic disease group took up the offer if the jab.
"We believe influenza vaccination should be encouraged wherever indicated, especially in those people with existing cardiovascular disease," they write.
"Further evidence is needed on the effectiveness of influenza vaccines to reduce the risk of cardiac events in people without established vascular disease."
The Lancet Infectious Diseases October 2009
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