this may sound a little crazy, but kleenex or paper napkins kept in the pockets of your coats and ALWAYS used to protect your hands when opening public door handles and turning knobs is by far the best prevention method I use. i use anything but my bare hands to open a public door.
picture a sick person sneezing into their hand and then using same hand to open the door.
then poor unsuspecting you enters next. then your nose itches...and that's all she wrote.
i used to get sick all the time, but since i adopted this prevention habit, it is rare that i pick up a bug.
hot green tea and honey is the fluid of choice for recovery.