Defining COVID-19 Terms: Antigen Test

August 17, 2020


Elizabeth (Izzy) Montgomery, MPA
Policy Analyst

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In this installment in our series explaining key terms and phrases used by public health officials in discussions of the COVID-19 pandemic, we look at the term “antigen test.”

As the state continues efforts to broaden its COVID-19 testing capacity, antigen tests have often been discussed in recent news stories. Antigen tests, also known as rapid diagnostic tests, are used to diagnose active coronavirus infections.

In a previous post, we discussed the difference between molecular and serological tests. Like molecular tests, antigen tests are a type of diagnostic test. However, molecular tests typically use a method known as reserve transcription polymerase chain reaction, or RT-PCR, to detect the virus’ genetic material in a sample; in contrast, antigen tests detect molecules on the surface of the virus.

There are advantages and disadvantages in using antigen tests. Antigen tests are able to yield results more quickly than RT-PCR tests, much like rapid-result influenza tests. But antigen tests, though typically accurate in determining positive infections, have a higher false negative rate than RT-PCR tests.

Recently, the Arkansas Department of Health (ADH) published a testing primer which explains the different types of COVID-19 tests and when they should be used. As noted in the guidance section, ADH only recommends the use of antigen tests for people who are symptomatic as opposed to those who are asymptomatic or presymptomatic.

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