'Normal' flu
or what's known as seasonal flu, normally will not harm healthy individuals. They may be ill for a bit (I know - I was once off work for 3 weeks with flu) but it's not usually fatal. It tends to kill only the weak and immuno-compromised sectors of the population.

Pandemics comprising a new strain though are more likely to kill healthy young people with a robust immune system. I believe this is because the immune response causes lots of fluid to develop in the lungs, and this can lead to secondary complications like pneumonia, which can result in death.
( K2k6 has a proper job these days, Thu 30 Apr 2009, 8:37, Reply)