How Antibody Tests Work
Rapid antibody tests have three steps:
- A blood sample is taken from the patient, either through a regular blood draw or through a finger stick.
- The blood sample will be applied to a test strip and exposed to a small sample of the virus’s antigens, which will “simulate” the presence of Covid-19 in the blood.
- After a couple of minutes, the test strip will show whether SARS-CoV-2 antibodies are present.
Rapid testing usually takes 15-30 minutes. The procedure is very similar to antigen testing, as it involves a test strip and results are easy to visualize.
When you’re infected with a virus, the virus will thrive by creating copies of itself, which will spread through your body. In the case of Covid-19, these virus cells will mostly concentrate in the respiratory system. That’s why diagnostic tests usually take samples from the respiratory canal: That’s where the virus’s genetic material is bound to be.
When the immune system detects a viral attack, it produces proteins called “antibodies”. These antibodies bind to a virus to prevent it from creating copies of itself.
Through a test sample, an antibody test will detect two types of antibodies:
- The antibodies that your immune system produces in the first days of the infection (IgM)
- The antibodies that exist in your bloodstream to protect you in the future (IgG and IgA).
There are two types of antibody tests: Qualitative tests and quantitative tests. Qualitative tests give a positive or negative result. They’re great for determining whether you’ve had Covid-19 in the past. Quantitative tests, on the other hand, determine the concentration of antibodies in your blood.