I read a really neat article today about the common cold. There are actually 101 different viruses (rhinoviruses) that can cause a cold. Once you are infected by one of the viruses your body makes an antibody for that particular virus and you are immune from future infection for that virus. (I know that was an awful sentence, but I am too tired to fix it.) If you could be infected by a different virus twice a year after 50 years you wouldn't get colds anymore.

This is also the reason why there is not cure yet for the common cold; there are just too many different cold bugs and they all work just a little bit differently.

Having said that they have invented a medicine that would either prevent or cure (I forget which) a large majority of cold strains, but not all of them, but the FDA will not approve it. The reason: a side effect is that it interferes with the birth control pill's effectiveness and they deem that too negative of a side effect when weighed against the benefits of the drug. Now you know.