Its pretty simple. Keep away by sick people. Or, wash your hands with soap. The reason so many people get sick during the winter is because everyone stays indoors, and they come into greater contact with germs and stuff. Also, vitamin C will only help with the nasal membrane when you are sick, and not the cough.
The most effective immune boosting supplement I have taken is olive leaf - it works especially well on flu. However, it nows tends to upset my stomach, so I stopped using it. That may well not happen to you - I recommend that you give it a try.
You views on immune boosters alarm me greatly gentlemen. Esquire & Alaaro: be very very careful of vitamin c tablets. They acidify the mucus in the human body. They are more harm than good: - they flush out vital body minerals. Please stop using them. Mike C: be very careful. ln which form are you taking your garlic. Using Garlic is foolish. lt has more problems than benifits. Raw garlic oxidises the blood and turns it black. lt causes alot of free radical damage. Avoid it. (There is lots of research about garlic, just look it up. l don't have time [right now] to provide some research articles and juicy talk). This is just quick comments here. Esquire: there is alot more to getting sick than staying in doors. lt has everything to do with ammune system function. l will admit that staying inside is an immune killer though: studies have found that a person gets 800% more chemicals inside [their home] than outside. People that live within 400 yards of a main road are exposed to 2,000% more pollution than people living 5 mile away from a main road. (Please note: these figures l quoted are rough quotes [l can't remember exactly off the top of head] however they are reasonably correct.