https://www.bbc.com/news/live/world-53886479
"Hong Kong scientists report the first confirmed case of an apparently healthy patient being re-infected with Covid-19, four months after the first infection"
https://www.nytimes.com/2020/08/24/w...ronavirus.html
Not good, but both infections were mild; and it seems the immune system is triggered more after serious infections and the 2nd was without any symptoms - making it likely that the immune system at least partially stopped the 2nd infection.