Fact Check Friday: How COVID-19 tests differ

Posted at 9:45 AM, Nov 20, 2020
and last updated 2020-11-20 10:45:04-05

Coronavirus tests differ in several ways, including the type of test, what they detect, turnaround time and accuracy.

One type of test is diagnostic and tells the patient if they have the virus. The antibody (serology) test tells a patient if they’ve had COVID-19 in the past.

But there are actually three tests out there. The diagnostic test is broken into two categories: Molecular and antigen, according to the Food and Drug Administration.

Both are usually sampled using the nasal swab, but there are some differences.

The molecular test is highly accurate and usually does not need to be repeated. Results can come back in as little as 24 hours but could take up to a week or longer.

The antigen test results can come back in less than 30 minutes. A positive result is usually accurate, but there are some issues with false positives.

A negative result may need to be confirmed by using a molecular test as the antigen test is more likely to “miss an active infection.”

The antibody test uses a finger prick or blood draw. These tests are known as rapid tests.

Many results come back the same day, but sometimes a second test is needed for accuracy.

The FDA says “antibodies can take several days or weeks to develop after you have an infection.”

The FDA also “cautions patients against using the results from any serology test as an indication that they can stop taking steps to protect themselves and others, such as stopping social distancing or discontinuing wearing masks.”

The FDA just approved an in-home diagnostic test available by prescription.There is also a combination test that can spot both influenza and coronavirus.

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