For a lot of people, the message of this study is that now there's one more reason to get a flu vaccination. But Siriwardena the scientist has a slightly different analysis.

"The take-home message of this study is really that we need to do further research to look at this link between flu and heart attack to see whether there's a real cause-and-effect here."

The study by Niroshan Siriwardena and colleagues is published in the Canadian Medical Association Journal.