Flu vax may halve MI risk
INFLUENZA experts are calling for reassessment of the national vaccination program following research revealing that the flu injection almost halves the risk of myocardial infarction in middle aged people with ischaemic heart disease.
A study from the University of New South Wales found that, in 559 patients aged over 40 and referred to a Sydney hospital over three years, the risk of acute MI decreased by 45% in those patients who had been vaccinated.
The 50–65 age group is currently not included in the national vaccination program, although the authors believe that extending the schedule is worthy of further investigation in the light of this new evidence.
Lead author Professor Raina MacIntyre, an infectious diseases epidemiologist at UNSW and a director of the Influenza Specialist Group, said that such an extension had previously been considered not to be cost-effective.
“Prevention of cardiovascular disease, which is the leading cause of death globally and in Australia, and causes a great deal of illness and death in older adults, wasn’t taken into consideration in such estimates,” she said.
“Given the huge burden of coronary artery disease in society, even a small effect of influenza vaccination in preventing [MI] may have a significant population health impact.”
After taking into account other influential factors, such as age, high cholesterol and smoking, influenza did not increase MI risk but vaccination against the infection did seem to be protective.
Previous research had indicated that infections such as influenza might encourage blood thickening or prompt an inflammatory response in arteries that are already diseased, so sparking the development of a blockage.
The authors added that vaccination of people with a first MI could also have a significant impact, considering the high rates of subsequent acute coronary events in such patients.
“At the very least, clinicians should be aware of influenza and infection as an underlying and poorly diagnosed precipitant or comorbidity in hospitalised patients,” they wrote.
Heart 2013; online 21 August