Coronavirus antibody tests or serology tests can detect whether someone was exposed to SARS-CoV-2 or not. This virus causes COVID-19, and when our body detects the intruder, it starts producing fighters (antibodies) that supposed to be detected by the antibody tests.
The serology tests are detecting if our immune system was attacked by a virus, rather than doctors checking if someone has symptoms or not.
Antibody tests are a fast way to find out how many of us have developed immunity to COVID-19 and are eligible to go back to work.
However, scientists still don’t know how long can that immunity protect an individual from reinfecting. Accurate antibody tests are both, sensitive and specific. A sensitive test detects a large number of people who were infected by the virus, with or without symptoms, while specificity means showing as less false positive results as possible.
False positive antibody test result means detecting coronavirus antibodies when they don’t exist in the system, which is extremely dangerous.
Newley infected individuals are usually showing negative results. The reason for this is the immunoglobulin M that shows up in our blood a couple of days to a week later after we get infected, and immunoglobulin G, an antibody that can be detected several weeks after the infection.
Antibody tests can’t be used for diagnosis because they can’t detect a virus, but they are efficient in telling us who was infected by COVID-19 and if they developed immunity, and how long ago.