If you are wondering about taking a coronavirus antibody test, here’s what you need to know:
You may hear it called a serology test. It looks for certain things called antibodies in your blood. Your body makes these when it fights an infection, like COVID-19. The same thing happens when you get a vaccine, like a flu shot. That’s how you develop immunity to a virus.
The antibody test isn’t checking for the virus itself. Instead, it looks to see whether your immune system—your body’s defense against illness—has responded to the infection.
What are Antibodies?
Antibodies are the body’s way of remembering how it responded to an infection so it can attack again if exposed to the same pathogen. People with antibodies in their blood have immune cells available to fight the virus, which lowers the risk of reinfection.
How Tests Find Coronavirus Antibodies
To create an antibody test, researchers isolate specific parts of the genetic material from a virus that correspond to the virus' outermost vulnerable layer – the place where antibodies attach themselves.
According to reporting done by USA Today, “Once researchers isolate specific parts of the virus' genetic code, or RNA, they inject it into other types of mammal cells to make those cells grow with the same structure, or outermost shell, as the novel coronavirus.”
How to test for coronavirus antigens
The entire virus structure is known as an antigen – a foreign substance that engages the immune system. An effective lab-grown spike protein would have the same shape as the novel coronavirus.
Health care workers take a sample of a patient's blood and isolate the parts of the blood that contain the antibodies into a serum. If a patient has coronavirus antibodies, they would be found in the blood, along with the other antibodies.
Other tests can involve just a simple finger prick to draw a blood sample, which is collected with a plastic straw and deposited in a small cartridge along with a special solution of liquids that will cause a reaction. Ten minutes later, the test promises to tell you whether you've had COVID-19.
These tests are one of many antibody tests the FDA approved under its Emergency Use Authorization, which means they haven't been thoroughly reviewed by the agency and are not guaranteed to be accurate.
In a clinical evaluation, Zhejiang Orient Gene Biotech reported the finger-prick tests to be 61.8% to 94.4% sensitive, depending on the type of antibody that shows up in the test results, which means that the tests are reported to give accurate results 61.8% to 94.4% of the time.
So, there you have it: Yes antibody tests are fairly accurate, and it is likely that having coronavirus antibodies reduces your risk of infection. But researchers are still not certain that antibodies equal immunity and that having antibodies guarantees you cannot get infected again. So, even if you have tested positive for coronavirus antibodies you should still practice responsible social distancing and isolation until federal and state restriction have been lifted.