One of the issues is that we conflate "antibodies" with "immunity". Antibodies are something we can measure so that's why there's been so much emphasis on them.

One of the issues is that we conflate "antibodies" with "immunity". Antibodies are something we can measure so that's why there's been so much emphasis on them. But they do naturally diminish over time. Long term and durable disease immunity comes from B-cells and T-cells. They create antibodies when they run into an infection they've seen or even not seen before. Unfortunately those are difficult to measure. Good recent podcast from Dr. Peter Attia discusses this (How B cells and T cells work together to defend against viruses [22:00]) https://peterattiamd.com/covid-part2/ https://peterattiamd.com/covid-part2/