Immunisation Coalition says this year's flu season is one of the worst on record, with 486 deaths and more than 228,000 cases.

The group is hoping to not only raise awareness of influenza's potential to trigger heart attacks, but the flu jab's ability to reduce the risk of a heart attack by up to 45 per cent.

The body's immune response to influenza involves releasing chemicals called cytokines, which increases the risk of blood clots which can block coronary arteries.

This limits blood supply to the heart and can cause a fast or irregular heartbeat.

Research shows a person is six times more likely to have a heart attack the week after having the flu, compared to the year before or after the infection.

Tim Tan from Blacktown Hospital's department of cardiology says people who have not had a flu jab are almost twice as likely to have a heart attack, compared to those who have been vaccinated.

The associate professor says people at risk, such as those with cardiovascular disease, asthma, chronic obstructive pulmonary disease or diabetes, should get the jab.

"Our significant concern is the rates of flu vaccination in the under 65s - which remain very low at just 30 per cent," he said.

"It's important to act now. It's not too late."

Heart Foundation's Bill Stavreski says the symptoms of a heart attack - nausea, chills, aches and sweats - can be confused with signs of influenza, and vice versa.

"Any of these symptoms, particularly in at risk groups, must not be taken lightly - especially where there is a history of cardiovascular disease," he said.

"Medical attention should be sought immediately."

Australian Associated Press