Regular antibody test? I assume so. T Cells are the long term immunity. There is a test for them. It is pretty safe to assume given her immune response she is teeming with them. There is a T Cell test that can be had. Your MIL is right to be nervous about taking the vaccine when she has natural immunity and had a very robust immune response to the getting Covid. If I were her, I would lean towards the J&J one if I took any at all. The 2 shot version with its challenge, response model for someone with natural immunity seems to be asking for problems. See the comment upthread about the posters experience as a shot provider. The ones who get sick from the vaccine had Covid before.
Thank you. That was my reasoning as well. One of my daughters is due for her 2nd Pfizer. Gonna see if I can talk her into getting abs checked first :)