Apparently there are 3 types of Covid 19 tests.
1. Nucleic acid amplification tests ( molecular tests) - also known as genetic, RNA or PCR tests. 2. Antibody tests - also known as serology tests. 3. Antigen test
Diagnostic or PCR test. This is the one with the long stick getting mucus from your nose. Even though it takes a few days for the virus to replicate in the nose, this method is so far the most reliable one.
Antibody test. This is a blood test to look for antibodies to the virus. Since it takes time (at least 4 days) for your body to generate antibodies, and without FDA authorization, the result may not mean much.
Antigen test. This method tries to detect proteins from the virus in nose. It is a quick screening test for just a few minutes, but accuracy is still to be determined.
ref: https://asm.org/Articles/2020/April/COVID-19-Testing-FAQs https://www.npr.org/sections/health-shots/2020/05/01/847368012/how-reliable-are-covid-19-tests-depends-which-one-you-mean