There are multiple documented cases where a person caught COVID twice (where the two instances were genetically different, and therefore not a false positive caused by lingering dead virus).
The linked article only indicates that antibody production should continue for a long time, but that's only one factor in robust long-term immunity. The rate of antibody production and the set of proteins that the antibodies target are also very important.
It's good news to be sure, but it doesn't yet prove what you seem to want it to.
> There have been far more breakthrough cases of fully vaccinated people than there have been confirmed reinfections.
Yeah, but there are vastly more vaccinated people than people have been confirmed infected even once, so that doesn’t really tell you anything. (Currently, the number of vaccination doses being delivered per day globally is about 1/5 the total number of confirmed global COVID cases.)
We'd need to compare the number of confirmed reinfections divided by confirmed infections with the number of breakthrough cases divided by the number of fully vaccinated people.
Its also worth noting the confirmed reinfection count is on a much longer time scale than breakthrough infections. So we currently have more data about the long term natural immunity than we do for vaccinated immunity.
I don't see the relevance of whether the re-infection cases are symptomatic. If anything, this makes it slightly more important to be careful, because asymptomatic transmission is what makes this virus worse than others of similar lethality. I don't think that's a significant factor, though.
The linked article only indicates that antibody production should continue for a long time, but that's only one factor in robust long-term immunity. The rate of antibody production and the set of proteins that the antibodies target are also very important.
It's good news to be sure, but it doesn't yet prove what you seem to want it to.