This is all highly speculative theory, but it seems to fit the discussion.
I tend to take the AV stance on viral illness, and view viral outbreaks as a necessary though sometimes painful and unpleasant cleansing process, at the very least. I suspect there may be a more divine purpose at work within the biological matrix which virus are an integral part. Imagine the possibility that the emergence of a virus is triggered by some type of internally driven genetic response to environmentally adverse circumstances. By spreading through the population and inducing similar purgative reactions in other members of the same species, perhaps viral outbreaks are a way of maintaining genetic homogeneity and viability within the population as a whole. Not only do they cleanse and purge, but the can also alter the functions of our DNA leading to mutation and contributing to the process of adaption and evolution. Those organisms within the population who are in most need of purging waste or coping with deficiency or imbalance will of course have the most severe reactions, while the purest and most physically and genetically robust may only have a slight sniffle.
This is why suppressing viral outbreaks artificially through drugs and vaccines, due to the ignorance of the medical establishment is so insane. Evidence now shows that children who are not allowed to go through the childhood viral cleanse, such as chicken pox, hpv, measles, etc; while at the same time being shot up with genetically engineered viral strains, are being genetically culled and mutilated. This generation being raised in the age of socialized medicine as a result will be more prone to degenerative diseases that are now starting earlier in life. Their offspring will be less able to naturally adapt to environmental change, and it will ultimately lead to a Devolution of the species if these conditions of ignorance persist.
Medical science is either suppressing these new discovers, or perhaps is just ignorant of the implications of such an alternative theory. Either way the results are devastating.
There is still so much that isn't understood about viral illness, that its ludicrous for anyone PHD or Caveman like myself to make assumptions regarding causation of the common cold. From personal experience I can say that after going raw paleo my own chronic viral outbreaks have ceased. The year prior to going raw paleo I caught hand foot and mouth disease, viral meningitis, swine flu, and K-9 pravo. These were some severe purging reactions, it was a painful hell that I thought I wouldn't escape from. Looking back, honestly I think it was all biologically necessary(pain is just weakness leaving the body) and for all I know it may have lead to some kind of mutation that will better the next generations chance of survival in this ever changing world. Whatever the case was; These chronic recurring outbreaks have ceased after going paleo, and now when everyone gets full blow cold, I will often feel just a little off for a day, if any symptoms at all.
There are so many factors and co-factors involved that no one can be sure, considering how complicated the world has become in these post paleolithic epochs, but I believe that personally my chronic viral sickness was a combination toxicity and nutritional deficiency. These are the big two factors to consider. The dynamics of these two factors are different in every individual case, so much so, that modern medicine has yet to fully understand the implications and complications of such revelations as it pertains to treating diseases of civilization ;or even the common cold.