New system for ranking flu severity

In the wake of all the flu warnings we've been hearing for the last several months, federal health officials have released a new system for ranking the severity of the flu outbreak each flu season. Developed by the CDC and called the "pandemic severity index," it's designed to both weigh the risks of an expected outbreak and also give advice to local officials on how to handle it (i.e. school closings, quarantines, etc).

The new system would rank flu outbreak severity on a scale of 1 to 5, with 1 being the most mild and 5 being the most severe. The hope is that if there ever is a true flu epidemic, this system can help government and health officials react in the best and most efficient way. I know the flu is a real threat, and the need for a system like this is no surprise, but still -- it's a little scary.