Which COVID-19 Test Am I Getting?

There are two types of testing available for COVID-19: an antigen test (infection) and an antibody test (immune response). If you received a test at one of the “Testing Blitz” locations around the state on either May 2nd, May 8th, and May 16th, you received an antigen test to see whether or not you have an active infection of the virus. 

Antibody tests on the other hand, are beginning to be administered at the University of Arizona, along with certain testing facilities across the state. As antibody tests become more available in the coming weeks, you might wonder

What is the difference between an antibody and an antigen?

  • These two terms sound very similar, but they have key differences. An antigen is a molecule that is part of the virus. These are present in your body during an active infection, while antibodies are proteins present in your body after an illness. This means that antigens can tell us if you are sick right now, whereas antibodies take time for the body to make and can only tell us if you were exposed to the illness in the past. 
  • When you are exposed to a pathogen, such as the COVID-19 virus, your immune system works to fight off the illness by producing antibodies. These antibodies are proteins that can help defend your body from germs by creating an immune response to the pathogen you were exposed to. That means if you are exposed to the same (or very similar) pathogen in the future, your body is more likely to recognize it and respond quickly.

What is antibody testing?

  • Antibody tests, also called serology tests, detect specific antibodies in the blood that are only made in response to a previous COVID-19 or similar coronavirus infection. These tests cannot diagnose COVID-19 in people, but rather show whether or not their body has been previously exposed to the virus. This is important because this gives an idea of how many people have had an exposure that led to an immune response to the virus.

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