"Collagen likely is not much of a factor, but vitamin C can get depleted easily during an infection. The stronger the infection, the more vitamin C is lost - especially if inflammation is involved." When vitamin C is depleted (for whatever reason) collagen is involved and the potential for scurvy and other diseases increases. Injections might be required to avoid the immediate effects. Others here have already reported on the many other effects that Vitamin C might have, the medical community's skepticism notwithstanding. Linus Pauling was a leader in promoting vitamin C for good health and he suffered the disdain of the medical community. That said, the ad hoc virtues and effects of ascorbic acid need clinical study.