How coronavirus antibody tests work and why they matter

In the fight against the coronavirus, there is still one big unknown: how many people have actually contracted it, maybe even without showing any symptoms?
One way to answer this question is through antibody tests. An antibody is a protective protein produced by the immune system to destroy harmful viruses and infections. When a pathogen enters the body, the immune system recognizes it and produces antibodies that dock onto the pathogen's antigens to remove them. Later a blood test can be used to detect these antibodies in a person's blood stream.

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