immunity, which we don't other than via studies like this one. We just assume the vaxxed have kept their immunity, even though over time we've learned that hasn't held up as much as we hoped. (not intended as a criticism, just what it is) Maybe better and more testing available?

I'll leave that to the actual experts that know much better than any of us here. But the point remains, it seems we should be considering natural immunity as much, if not more, than vax immunity.