Quote Originally Posted by KnottedYet
Supposedly there are only a limited number of cold viruses out there (like 130 or so). And after you've had one, you won't react to it the same way the next time your immune system encounters it because you've built up antibodies to that particular virus's protien coat.

So get out there and hug those kiddies! Kiss their sweet little hands! Love them like they're your own, for are they not all OUR children with precious little souls? Fear not, for ye don't walk in the shadow of the valley of Death, ye only have the real world to cope with and a limited number of colds for your lifetime. (bacteria in hospitals, though, that's another icky story entirely )
Actually, that's not quite true. While there are a limited number of viral pathogens that cause "cold" symptoms (fever, sore throat, myalgias, etc), and in THEORY your antibodies to those viruses should protect you, it is utterly impossible to protect yourself from the common cold due to the high rate of mutation among viruses.

Viruses mutate so rapidly, you can catch the exact same virus at the begining and at the end of the flu season. All it has to do is rearrange little RNA or DNA, and its antigens can change ever so slightly. Once those antigen(s) change, your body has mount another host reponse to it and produce new antibodies all over again. Bacteria do this too, but at a much slower rate. possibly due to a longer replication cycle.

Evolution, baby. Gotta love it. Life will find a way.