COVID-19 immune response testing checks for immunoglobulin G (IgG) that is a result of past COVID-19 infection. This antibody can be detected 14 days after exposure to the virus through a simple blood test. THIS IS NOT A TEST FOR ACTIVE COVID-19. The FDA has authorized antibody testing because: • Antibody tests can help to identify those who have previously, possibly unknowingly, been infected with the virus and may have developed an immune response. • Knowledge gained from o