Where do the critters go after flu season? Do they self destruct after a peroid of time? It seems that they would keep on infecting & mutating to return to re-effect it’s former victims not immune to it’s new guise. Does a lowering of the immune system due to cold & chill invite infection? I’m told that cold is not a factor. I believe it is.
The official word on why there are more colds and flus during cold weather is “we don’t know.”
There are speculations about various things, including the belief that cold weather depresses the immune system, that we stay inside more, that children’s returning to school exposes them to more infectious agents, that less UV in winter kills fewer viruses, that we spend more time inside with other people, and on and on.
Those are all speculations. None have actually been proved.