There is one right in the list on the CDC page you linked[0]. There is also a recent Nature paper[1] that shows that T cells levels are stable for at least the

There is one right in the list on the CDC page you linked[0]. There is also a recent Nature paper[1] that shows that T cells levels are stable for at least the first 100 days they observed. I don't know of a specific link to send you for that, but that usually indicates T cell immunity on the timescale of multiple years (otherwise some drop in levels would have already been visible in the observed time period). [0]: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7427556 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7427556 [1]: https://www.nature.com/articles/s41591-020-01143-2 https://www.nature.com/articles/s41591-020-01143-2