This report states that unless you are highly stressed (skier in cold or a soldier) or take large doses, Vitamin C does not prevent or reduce the severity of colds.
Of course, what the report could have said is that if you are a strength athlete, working out hard regularly, and working, & living your life, that your level of body stress may be enough to enable the cold-prevention qualities of C to help you.
And instead of saying that doses less than 8 grams at the onset of a cold didn't prevent a cold, they could have said "Take at least 8 grams on the day you start to feel a cold come on and you may not catch it".
I personally have no problem taking 8 grams throughout the day if I start to get that feeling you get when catching a cold. If your body can't use it, it will just excrete it naturally. Why the reports perspective was from a negative slant towards C is anyone's guess, and maybe I'm cynical but the pharmaceutical industry sometimes has a part in these 'news' stories, since they can't patent a natural vitamin like C.
Anyway, off my soapbox. Remember that vitamin C is also a powerful anti-oxidant that works in concert with E reduce cell damage while you age and helps repair sun and pollution damage caused by our environment.