@notacat speaking of those -- there is evidence that SARS-CoV-2 sticks around and causes chronic T cell activation, and there are only so many naive T cells the thymus can supply before it shrinks (it normally shrinks with age)

This implies that all covid infections, even those that don't produce obvious long covid at first, may be prematurely aging the immune system

https://www.medrxiv.org/content/10.1101/2023.07.27.23293177v1.full