Following up on Doohickie's thoughts, I heard a doctor on NPR radio talking about it yesterday.

On average the U.S. has 36,000 deaths from flu per year, the vast majority being among the old and already compromised. It isn't the flu that usually kills them but a secondary thing such as pneumonia. One point being that our more common flu variety seldom kills basically healthy people. The swine flu may be another matter.