Doctor Decoded: What Are Antibodies?

Testing has been a major topic of conversation during the COVID-19 pandemic. Finding out if you are actively infected with the novel coronavirus can be very beneficial, since those who are carrying the virus should self-isolate at home to avoid spreading the infection to others in the community (or even the household).

But as the weeks passed in April and May of 2020, the conversation started to include antibody testing. How is that different from a regular, nose-swabbing COVID-19 test?

Antibodies are like souvenirs from your immune system. If your body was like a fridge full of souvenir magnets, you’d see magnets of some of the diseases and infections you’ve conquered (or been immunized against). You’d probably find a measles magnet, a chickenpox magnet, etc.

More specifically, antibodies are proteins produced by the body that help destroy toxins or pathogens that endanger your health. Once the infection or disease passes, you may still have the antibodies in your body (but not always, depending on the disease).

For many diseases, having the antibodies in your system gives you natural immunity. This means you’re protected from getting the same disease again—sometimes just temporarily, and sometimes for life. These antibodies are called neutralizing antibodies.

This is also how vaccines work: You get an attenuated or weakened version of the virus, which triggers your body to produce protective antibodies (without giving you the infection itself). If you got the measles vaccine, for example, your body would be triggered to produce neutralizing antibodies against the measles, protecting you from getting the disease in the future. This is vaccine-induced immunity.

What’s the Deal with Antibody Testing?

Testing for antibodies can serve a number of purposes. It can be used to diagnose diseases like human immunodeficiency virus (HIV) or hepatitis, both of which do not cause symptoms right away but still need treatment to slow the progression of the disease. Antibody testing can help diagnose HIV by testing for the antibodies your body is producing to try to fight the infection. (Learn more about testing for HIV here.)

As for COVID-19, antibody testing has the potential to find out who has previously been infected with the coronavirus. Because there have been asymptomatic carriers of the virus, antibody testing for COVID-19 can help with:

• Identifying who has had the virus without knowing it

• Providing more accurate statistics about infection rates

• Researching if having antibodies help provide future immunity (i.e., if you can only get COVID-19 once)

• Analyzing how safe it is to resume businesses, schools, events, etc.

But again, it’s important to remember that antibodies vary, and not all antibodies provide protection. As with many aspects of this new disease, there’s still a lot to learn about COVID-19 antibodies.