Some researchers are looking to T-Cells in your body which can fight virus. They think that if you don't generate antibodies, you might have a level of defense from your T-Cells. However, to see how much they would help, you would want to quantify how many T-Cells you have. Perhaps more T-Cells, more immunity, but will take years to research whether they would work against CV19. I think T-Cell count is an expensive test now and needs a lab, is not portable.