Originally Posted by
leoo
This is weird. My understanding is that an antibody test can return a negative result even if you're fully vaccinated.
Depends on the antibody test. As long as the test focuses on the same protein as the vaccines to test for antibodies, it should work. You can test for antibodies using a number of different proteins from SARS-CoV-2. I believe most if not all of the vaccines use the spike protein to create antibodies, thus your antibodies react to that spike protein. If you test using a different protein from the virus, it won't trigger an antibody response even though you do have antibodies that will correctly react to the virus.