I don't quite understand your logic, but the more common view is rather the opposite: repeated small exposures are the best way to get exposed, if you cannot av

I don't quite understand your logic, but the more common view is rather the opposite: repeated small exposures are the best way to get exposed, if you cannot avoid it completely. The mechanism is essentially variolation: giving your immune system some exposure so the adaptive immune system can start the process of building immunity, but so little that the innate immune system still has a good chance of winning this first round. Then, of course, there's basic mathematics: viruses multiply exponentially. Assuming a single virus particle can theoretically infect you and, at the other side of the spectrum, that getting full-on sneezed on can deliver a billion virus particles, the time difference is enormous: that one virus particle would take 30 viral life cycles to grow to a billion, even if unchecked. At a few hours per generation, this could provide your immune system with a few days to a week of head start.