Influenza - How to prevent a flu

The flu is going around throughout Japan.
We have type A, type B, and a new type. I do not know which one I got last week. My badminton mates were discussing (while practicing..) about how to prevent the flu.
It is commonly known that people over 60 do not get the flu because they are immune to the flue today, but according to a teammate, people who used to drink "Dassi Funnyu" also have less risk to catch the flu. "Dasshi Funnyu" can be literally translated as skim milk or fat-free milk, but in fact it is something that tastes much worse than those. Dasshi Funnyu, skim milk,  were brought to Japan after WWII by U.S. Government as a part of aid supply and they were provided to children as school lunch. We should appreciate the kindness of Americans, but... it seems that they did not care about its taste as much as its nutrition value..... So Dasshi Fyunnyu is regarded as synonym for slop food (sorry!) in old days. Anyway, it is considered that Dasshi Fyunnyu was supplied at Japanese schools mainly in 50's and 60's. Again, thanks to American, now it is said, whether it is just a rumor, Japanese who took the food in childhood may have less risk to catch the flu!
However, the best way is to prevent the flu is still washing hands and gargle throat.

I think Japanese is the people who like gargle most.　We gargle frequently, saying we might have a cold or the flu, or we have hay fever, or we feel dry throat. We gargle everywhere; in the bathroom at office, school, department store, or airport. Solt water gargle is the most common, but green tea is also used for gargling because it contains catechin which kills germs. Diluted iodin solution is popular, too. One of the amazing way to rinse out your throat perfectly is gargling from nose! You suck in the gargle water from nose and spit out from mouth. I tried once when I had very bad sore throat from the flu. I forgot the pain in my throat due to the  terrible feeling in my nose.
* But you may want to try (^_^) since it worked!