People like simple theories. But many things are complex. People like the theory that a germ causes a virus. But the whole theory includes the terrain or immune system. That is much more complex.
You will not get a flu or cold unless you need to. If they are good for health then what is bad for health. Guns do not kill people. People kill people. Drugs, like meth, do not jump into people. People put them into themselves.
Going by numbers little kids get the most colds and flus and live around another 65 years. Old people get them the least and live another 10 years. To the body only health matters. To the person many other things are more important like money, relationships and more.
For example a guy eats whatever he wants. He is too important or busy to get enough sleep. He cannot be bothered to keep stress down. Since he is stressed and unhappy he eats way too much. He has a terrible lifestyle and the flu is an incovenience.
But if you get sick enough, then you cannot eat much. Also you need to take off from your very important job and get a lot of sleep. What caused Mariah Carey's nervous breakdown? She said that she caused it with lack of sleep. Reports say that most Americans have sleeping problems.
Well at least people have no eating problems!
People can be thinner and healthier by exercising more, eating less and sleeping more. Studies show that sleeping more is more important than exercising more when it comes to losing excess weight.
October 2009, The New York Times reported on a study that found that those who get less than seven hours of sleep a night are three times as likely to catch a cold as those who sleep at least eight hours a night.
There are many more factors like getting enough vitamin D but this is enough for now. Vitamin C cured scurvy decades ago but it is not coming back
. Vitamin D cured cured rickets decades ago but it is coming back