The Disadvantages of Having the Flu:
1) You are reinforced in the desire for Cartesianism, already prevalent, which would separate the body completely from the mind.
2) The relationship between each layer of blanket and keeping it over you, after three days of thrashing around legs entangled in them, is more complicated than any mathematical formula and makes you doubt your already doubtful sanity. The only answer is to get up and make the bed again, but you can't. So you lie there and work out how to reorder the blankets properly while you are still entangled in them. This eventually affects the mind in permanent ways.
3) You learn to hate food, all food, and are well on the way to being one of the those chalked up sannyasins with no stomachs on the road to Benares.
4) People begin to get used to avoiding you like a leper, which carries over into future life (cf. Ben Hur or Donald Trump)
5) Since there are only 100 days of the year when any real work gets done -- Jan 15-June 1, Sept 15 - Dec 10 (excluding weekends, Friday afternoons, lunchbreaks, shopping time, coffee breaks, and holidays), 4 weeks sick in January means the loss of 1/6 of the working year, which messes up substantial parts of the other 5/6, unless you are very organized, and can begin to encroach on the other 265 days. This is how your brain works when you are sick (see disadvantage 2 for further pointers).

yours, Peter T.