> researchers looking at SARS-CoV-2 antibodies in people who had recovered found that the difference between the highest and lowest levels varied by a factor of over 1,000.

Citations in: https://arstechnica.com/science/2020/06/antibody-testing-sug...

The average immune response to infection is good. But for some it's great and for others it is poor.

Answer is in the post you reply to. Might want to reread.