If people are constantly cleaning surfaces, anything that is touched, etc. with all that antibacterial stuff, then what hope do you have of fighting something off?? We need to be exposed to those 'little' things in order to build up the imunities we need to fight off the big stuff. So, wash your hands a lot, drink lots of fluids, get plenty of rest and eat sensibly. Then, off you go...have a good time in WDW. I do carry a little bottle of Purell with me but I don't use it very often.
According to both my doctor, and my dd's pedi, you are better off taking a regular vitamin every day, drinking lots of water and washing your hands more often than you are taking any of those other things ....like Airborne. But, that's just their opinion.