And flu outbreaks follow a predictable and natural spread pattern. That's why they track it by state and county. Flu has not, as far as I know, been spread "deliberately" at any time, although I think corporations and schools that force people to congregate with others when ill ought to be criminally liable for that.
But if you look back through my older posts on FR you'll see that I am a serious advocate for flu preparedness, also. Watch people in any public restroom. They go in the stall, they do their thing, they come out, they leave, usually rubbing their eyes or otherwise touching their faces with whatever virus they've unconsciously trolled for. Depending on location and education level, 1/4-2/3 of us do not wash hands, and those who do usually touch the doorknob on the way out (thereby making their handwashing rather moot.)
I don't want to have to try to figure out how to take care of someone sick with this. I generally have a clue about flu (and as an at-risk adult, I get my flu shot, so I'll be well if I have to take care of a child with flu.)