The Difference Between Antibody And Antigen COVID-19 Tests, Explained

Getting tested for COVID-19 is one of the most important things you can do to help prevent the spread of the novel coronavirus. There are several tests available, including the antibody and antigen tests. Although they may sound similar, the tests are actually quite different.

What is a COVID-19 antibody test?

A COVID-19 antibody test is designed to detect signs of a previous infection. This test takes the form of a blood draw that must be processed by a lab. Your results will typically return within 3 days of your test.

Can a COVID-19 antibody test detect an active infection?

Under certain circumstances, an antibody test can detect active infection. This can happen if your body has started producing IgM antibodies in response to the virus when you take the test. However, this test is NOT designed to detect an active infection, so you should get a rapid antigen or RT-PCR test if you think you have been exposed to the virus.

What are the benefits of the antibody test?

It may seem strange to get an antibody test if it only detects an infection after you’ve had it. However, there are several benefits to getting an antibody test.

Antibody tests are helpful because:

• You can help health officials gather data that, in turn, helps them offer better public health guidance based on the extent and spread of the virus by region.
• You can contribute to public knowledge of the SARS-CoV-2 virus strain, helping health officials better understand how the virus affects the body during and after infection.
• You can know if you’ve had COVID-19 so that you can return to work safely.
• You can donate convalescent plasma to help individuals who are very sick with COVID-19 recover.

What is a COVID-19 antigen test?

A COVID-19 antigen test is a nasal or throat swab that is intended to detect active infection. This test can be processed immediately, with results typically returning in 15 minutes.

Although this test is very fast, it’s important to know that it has a slightly higher rate of returning false negatives than the RT-PCR test. Still, a positive result from this test is considered to be quite accurate.

Is the antigen test the same thing as the RT-PCR test?

No. Although both the antigen and RT-PCR tests are typically administered as a nasal swab, these tests are different.

• The antigen test detects specific proteins on the surface of the virus.
• The RT-PCR test looks for specific genetic material and takes several days for a lab to process.