[dannyw]

While correlation is not causation, I find it interesting that the human immune system only remembers the common cold and seasonal influenza for several months, but diseases like the polio for much longer.

https://biology.stackexchange.com/a/21802

[TylerE]

"The common cold" is a loose nebula of hundreds of different, unrelated, virus strains. They're not even all the same TYPE of virus.