Abelardlindsey wrote..

My recent blood test showing a complete lack of covid-19 antibodies despite me having been infected 6 months previously suggests that antibody immunity does not last longer than 6 months.

I think this will vary from one individual to another. I know someone who had a mild case in March of 2020 who still had a strong antibody response in December. In fact, he wasn't certain that he'd had the Coof in March until the antibody test in December.

----------