We now have the best evidence yet that everyone develops long-term coronavirus immunity after infection — and it's not just about antibodies https://www.businessinsider.com/long-term-coronavirus-immunity-t-cells-2020-8
A rather remarkable paper considering many authors involved are closely linked to the Karolinska Institute in Sweden, which plays a major part in deciding who receives the Nobel Prize in Medicine each year.
This also shows why antibody testing isn’t the be-all, end-all by any measure...as you could very well be immune and not show a positive antibody test.