This is a “humorous” quip I sometimes see people making on social media: “Scientists have managed to eliminate smallpox, so why can’t they come up with a vaccine for the common cold?”
I have always assumed the reason was that there are so many different strains of the virus that causes colds, it would be nearly impossible to vaccinate against all of them. But that’s always just been a guess. I’d like some actual factual information to back that up.
I imagine there’s also just the fact that a cold generally isn’t an illness that kills people, and most scientists probably consider their efforts better spent towards more important things.
Actually the version of that quip that I know ends with…and there’s still no cure for the common cold! (or similar.) Except, of course, there is: Pleconaril. It works, too - efficacywise. But there’s more than that to getting a medicine approved.
The point being, in part, that the safety bar is set much higher for a trivial and self-limiting disease. (Not my line - wish I could remember who I’m quoting).