It has to be pointed out that the numbers who die are likely to be relatively small. The 1918 flu only killed 2 or 3% in a day when oxygen was rarely used and respirators were even rarer. Medical science has advanced a bit since those days and survival is expected to be better.
2-3% mortality may not seem like much... That is, until you or one of your beloved ones happen to be among those 2-3%.
Lately I've heard a lot of people talking about the swine flu as something harmless blown out of proportion. The mortality may be low right now but there's no guarantee it won't increase. Also, it is apparently very contagious and could affect a large part of the population. Who knows, maybe as much as 30%. At any rate, it could realistically mean a million (or millions) infected over a few months by a very conservative estimate. Even with just 0.1% mortality, that means a death toll in the thousands, with 1% death rate in the ten thousands. Those are serious figures.