(Quite confident) The most common illnesses (colds and flu) don’t build immunity in general (in kids or adults) because they mutate every year
Not my area, but it seems like the difference between “this year’s variant and last year’s” is going to be much, much smaller than the difference between “never exposed to any cold/flu before”.
So naively it seems possible that the first several colds do train the immune system quite a bit to handle colds in general, even if subsequent ones are then moving around to different points on the fitness landscape.
Yes. There are many different “cold” viruses, and adults have some degree of immunity against most of them, while children are getting many for the first time in their life. That’s very different from the flu, which doesn’t have many concurrent versions but is evolving more rapidly. (Not sure where covid falls here.)
Not my area, but it seems like the difference between “this year’s variant and last year’s” is going to be much, much smaller than the difference between “never exposed to any cold/flu before”.
So naively it seems possible that the first several colds do train the immune system quite a bit to handle colds in general, even if subsequent ones are then moving around to different points on the fitness landscape.
Yes. There are many different “cold” viruses, and adults have some degree of immunity against most of them, while children are getting many for the first time in their life. That’s very different from the flu, which doesn’t have many concurrent versions but is evolving more rapidly. (Not sure where covid falls here.)