A simple flu jab could halve the heart attack risk of tens of thousands of older Australians with narrowed arteries, according to new research.

A study published in the journal Heart shows the jab is effective at reducing heart attacks among people aged 50 to 64.

However, the age group does not automatically qualify for free vaccinations and there is compelling evidence for this to be reconsidered, says lead author Professor Raina MacIntyre from the University of New South Wales School of Public Health and Community Medicine.

In the past, vaccinations have been seen only as a way of preventing flu, but she says they should be looked at in the context of preventing heart attacks as well.

Previous research suggests that infections such as flu might encourage blood to thicken or prompt an inflammatory response in arteries that are already diseased.

This could lead to a blockage and a heart attack.

Dr Robert Grenfell, national director of cardiovascular health at the Heart Foundation, says most people aged over 50 are at increased risk of having a heart attack.

The foundation's position is that all people at risk of a heart attack should consider having a flu injection.

This includes people with high blood pressure, high cholesterol, those who have had a previous heart attack and people who smoke.

However, Dr Grenfell says Australians are complacent about the flu vaccination and there are many misconceptions about it.