Covid19 antibody blood test

Here's my test 4 months after contracting Covid19 moderately badly. As you can see the line at IgM has now disappeared as expected, but the line at IgG, which is the memory antibody, remains strong. Certainly I'm going to deduce from that I'm immune, also to the Kent variant (which I probably had) and the South African one. But how do I get a passport saying this?