@RedPowerLady: basically, there are two things contributing to the uncertainty here.
One, this is a variant of flu that most people aren’t exposed to often. It’s an H1N1 variant, where the flu that comes around each winter is something else—my memory says H2N3, but I’m not sure that’s accurate. So it’s likely to hit people harder than the annual flu.
Second, it’s at a time of year where the flu doesn’t usually hit, so people won’t be ready for it and it will probably spread in different patterns than the flu usually does.
The flu itself doesn’t kill people, but it weakens people, and they die from things like pneumonia or dehydration, especially if they are frail to begin with. Beyond that, this is likely to be a severe flu (because most people don’t have any resistance to H1N1 strains), and so it’s likely to take people out of commission for a week. So while there’s a lot of panic about deaths from flu, the real logistical problems that governments are worried about is going to be 25% to 50% of the population all being sick and staying home from work at the same time.
What happens when 25% to 50% of a city’s busdrivers are out sick simultaneously? Or police officers? Or supermarket cashiers?