So, following the trend of virtually every major global pandemic in history, Swine Flu started, spread wide, did little, and mostly died out. However, as is customary, eventually a strain mutates that is a significant baddy and is what does the real damage.
So it's now spreading again. While I don't expect any major catastrophe and I think young people like you or I have little to worry about, a lot of old people are going to die.
Also, check out how many people at PAX got infected:
http://www.penny-arcade.com/2009/9/7/feeling-sick/