My oldest sister (age 46) is hospitalized in intensive care due to influenza A. She is intubated, sedated, and probably going to spend a month or two in the hospital. And that's with the doctors being "cautiously optimistic". This is just from the flu. They checked, and it's not H1N1.
This sister is about as perfect as mortals come. She is an intelligent, generous wife, mother, sister, and community member. She looks out for her health, having followed the self-denying principles of The China Study for years. She doesn't smoke or drink. She exercises regularly, and as far as I can see, her only underlying health "condition" that could have contributed to her getting so sick is that she has seemed a little underweight due to her energetic focus on healthy eating and exercise.
I know illnesses like hers are relatively rare in middle-aged adults, but that is no comfort when they happen to someone I love. The best case scenario at present is that she loses a month of her life to hospitalization. I don't know whether she got the flu vaccine this year, but if there's a reader who's been thinking of getting it, I would encourage you to get the vaccine sooner rather than later. A fever for a day or two as your immune system develops immunity (the flu shot only has dead virus, and you can't get the flu from it) is nothing compared to full-blown, put-you-in-the-ICU flu.