We all want to know if we have been exposed and whether or not we are immune to the coronavirus ( SARS-CoV-2) aka Covid-19. Researchers at the Strasbourg University Hospitals tested people known to have been exposed to CV and discovered that you could be exposed, have the disease, recover and yet not show any evidence of anti-bodies to the CV. You will, however, be much more likely to show evidence of infection when tested for a T-cell response. T-cells are immune cells that can be activated when you are infected with a virus. It can be detected for about 80 days after recovery from the infection.
What this study implies is that a positive test for the antibodies most likely means you were exposed and are immune. What it also means is that if the test is negative, you could still have been exposed and may still be immune. So a negative antibody test may not be truly negative, known as a false negative, you may need a T-cell test also.