PCR TEST
This test detects bits of proteins on the surface of the virus called antigens. Antigen tests are typically considered rapid, taking only 15 to 30 minutes but are less accurate than a PCR test. Rapid antigen tests are most accurate when used within a few days of the start of your symptoms, which is when the largest amount of virus is present in your body. Because this test is not as accurate as a PCR test, if an antigen test is negative, your healthcare provider may order a PCR test to confirm the negative test result.
Antibody test: Antibody (serology) test: This test detects if you’ve had an immune response (antibodies) to the virus. This means that you’ve had the virus and your body (immune system, specifically antibodies) has mounted an attack to fight it. The test is detecting those antibodies. It typically takes about a week after being infected for enough antibodies to develop to be detected in your blood. For this reason, this test shouldn’t be used to diagnose an active infection."