Due to continuous testing being a crucial part of responding to the ongoing COVID-19 pandemic, it is important to understand the differences between antibody and antigen testing and how either can impact your health.
What is the difference between an antigen and an antibody?
An antigen is a molecule that has the ability to elicit a response from the body’s immune system. A virus, like SARS-CoV-2 that causes COVID-19, might be made up of different types of antigens that have their own distinct features when they react to the immune system. An easier way to think of an antigen is to think of any substance that your body does not recognize and tries to fight off. In addition to a virus, this might also include bacteria, pollen, or chemicals.
In response to our immune system reacting to an antigen, our body creates antibodies in order to respond to the foreign substance and act to fight it off. These proteins produced by B cells act in defense of your immune system to keep foreign substances, like viruses, out of the body. For example, if infected with SARS-CoV-2, antibodies are created to specifically bind with antigens related to the virus to help eliminate them.
What is an antigen test?
An antigen test tells a person if they are currently infected with a substance such as the SARS-CoV-2 virus. This alerts a person, as well as health care professionals, the correct action to take in order to treat a person presently infected with this antigen.
What is an antibody test?
An antibody test allows healthcare professionals to track the spread of certain viruses, such as SARS-CoV-2, and understand who might have already contracted the antigen by tracking past infections even if they did not show any outward symptoms. It can not be used to diagnose if a person is currently infected with COVID-19. This antibody test also helps for further action such as determining how long a person was infected, phases of infection, assessing herd immunity, and identifying those in priority for a vaccine.