S. Korea’s reinfections appear to be mild. There are a couple of pages of articles about the reinfections here: https://flutrackers.com/forum/forum/welcome-to-the-scientific-library/immunity-aa/848428-covid-19-reinfections-thread-207-cases-in-south-korea-saying-not-highly-infectious
It’s possible this isn’t even “live” virus, but virus RNA remaining in the body and causing the positive test. Let’s hope that’s the case. I heard of one case in SK where the relapsed person died, but that seems to be the exception.
But maybe the virus is living on in recovered patients. Considering the infection attacks so many organs, it shouldn’t be a surprise if there are viral reservoirs. If this IS active virus, that means it is coexisting with what are supposed to be neutralizing anti-bodies, and that could be a problem as antibodies fade. Or you pick something else up that your immune system has to fight, and CV19 is waiting to jump back in to action.
There is some evidence that the innate immune system response might be as or more important than the adaptive immune system. Maybe those taking supplements to boost their innate immune system have the right idea.
https://www.medrxiv.org/content/10.1101/2020.04.13.20040980v2.full.pdf