Antibody testing is usually ... a RT-PCR test to confirm a negative antigen test result. The FDA authorized for emergency use certain at-home COVID-19 test kits, including one that tests for ...

Antibodies are part of our immune system. They are proteins produced by white blood cells (B cells) that bind to and inactivate antigens - targets on viruses, bacteria and even our own cells.

Consequently, when antibodies are introduced into a body-fluid sample (for example, a blood or urine sample), they bind only to their target antigen molecules. Unbound antibodies are then washed ...