In general natural immunity is as good or sometimes better than a vaccine.

N=1 that natural immunity lasts long has to do with my 70+ year old dad who got covid Summer 2020 and has been doing blood donations ever since as he has type O blood. Every time he goes in they report back that his antibody count is still high. I can't offer you any studies on that, just a personal antidote.

Edit guess I'll get more minus points for my N=1 antidotes