I've seen a couple different news stories about the flu and stomach flu. One on the regular seasonal flu (cough, sneezing, aching body)and the other on the norovirus (aka cruise ship virus that has the vomiting and diarrhea). For the first this year's vaccine is very effective but takes up to two weeks for the body to develop the antibodies once you get the vaccine. And it does depend on the individual and their immune system. The second has no vaccine to prevent it and you can get it more than once. Of course neither is fun to go through. I was fortunate and got my flu shot back in October.
This is what I have heard also.
The norovirus is extremely contagious. It is not in our school at the moment (that I know of), but it hit a few years ago and everyone seemed to get it. They had trouble getting enough subs. Horrible projectile vomiting. I hope not to see that this year, although I know it is circulating.
The girl in Benton that died had the seasonal (cough, fever) flu. I don't know if she had a compromised immune system, but so sad and scary.