@raynbow- My mother swears by taking zinc throughout the fall and winter months for reducing her chances of getting a cold or flu. She does stay pretty healthy, but I don't recall her getting many colds or flues even before she started taking zinc.
I think sometimes avoiding these illnesses is just luck combined with other factors like eating a healthy diet, avoiding sick people, and getting plenty of rest.
If you do want to try taking a zinc supplement this cold and flu season, you should start with a low dose that will be less irritating to your stomach. Also, you should always take it with food, which should help prevent your stomach from getting upset.