Flu deaths are counted as the number of people who die because of the flu - that is, they represent people who wouldn't have died if they didn't catch the flu.

Flu deaths are counted as the number of people who die because of the flu - that is, they represent people who wouldn't have died if they didn't catch the flu. This is of course an estimate, and there are some pretty fundamental reasons why it has to be such as the fact that flu causes heart attacks and strokes but also just happens to be present in patients who have one for unrelated reasons, but it should be a pretty robust one because flu is an old and well researched disease and we have a vey good idea of how it behaves at a population level.