I did a T-Detect test. Their website states "A recent study demonstrated 95% of patients tested positive for T cells up to five months after a confirmed positive PCR test.1 Clinically validated data for T-Detect COVID performance beyond five months is not available yet." but it has stated this for months now.

I assume they are tracking how long their test detects T cells in subjects who had confirmed infections and hope they will provide public updates on this more frequently because "up to 5 months" is of limited value to people like me who were interested in knowing if they had the virus back in the earliest days of the pandemic.

Presumably the 5-month duration was based on the date of their 2020 submission for FDA EUA approval, relative to the earliest date of infection of their test subjects. If those early test subjects are participating in the ongoing trial of T-Detect, it's now probably a year since their infection & recovery. Hopefully we'll see a longer duration in their next FDA submission.

yes this is a good thing, the virus[sars2] has a feww features that allow partial stealth, and has accumulated variations that contribute to possible immune evasion.

this should not be taken casually, and perturberance of memory immunity should it occur would be a variant profile of high concern.