I was just wondering…
There must be loads of COVID viruses floating in the breeze. Even if one wears a mask, and practices social distancing, billions of these must be inhaled. Does the body slowly develop an immunity due to exposure to all of these viruses?
Yes, acquired immunity due to tiny-but-not-zero exposure is a thing.
Not so much.
There are people measuring and trying to estimate the level of ‘pre-existing’ COVID immunity, and they haven’t reported an un-explained rise in that number, so it seems that, at present, there aren’t a lot of people developing immunity without ever getting detectable (test result) disease.
This suggests that there isn’t as much COVID virus floating around as there is Pine Tree pollen, because in measurable numbers, people really do get pollen immune response from small amounts of Pine Tree pollen.