COVID-19 Testing 101: The Basics at a Glance

COVID-19 testing is continually evolving. However, it’s helpful to know the basics, such as the types of tests available and when each is used. Based on data from the FDA and clinical resources like this one, we’ve compiled an at-a-glance primer on COVID-19 testing basics (accurate as of blog publication date).

DIAGNOSTIC	TESTING	ANTIBODY TESTING
Test type	Molecular Tests (RT-PCR)	Antigen Tests	Serological Tests
What it measures	Virus DNA material	Virus proteins	IgM & IgG antibodies
Use to diagnose	Active infection	Active infection	Past infection
Reliability	Highly accurate but false negatives can occur	- Positive results are usually accurate - Negative results are less reliable and may require a molecular test	Past infection
How collected	Nasopharyngeal, nasal, throat and saliva (a few tests)	Nasopharyngeal or nasal (most tests)	High potential for false negatives and positives
Where	Lab, point-of-care and home	Lab, point-of-care and home	Lab and point-of-care
Prescription needed	Yes	Yes	Yes
Results	Minutes to 7+ days	Minutes to days (tend to be faster than PCR)	Often same day but may take several weeks
Approved Tests	FDA EUA list	FDA EUA list	FDA EUA list

Here’s more helpful information about COVID-19 testing:

All have Emergency Use Authorization (EUA) from the FDA.
The FDA cautions that a positive antibody test does not indicate immunity and COVID-19 precautions should still be adhered to.
Since false negatives are possible with molecular testing, it’s often best to treat a patient as positive if symptomatic, especially if there’s known exposure.
Pooled sample testing is sometimes used to save time and testing materials because multiple peoples’ samples are tested at once. It’s most effective when most samples are expected to be negative, such asymptomatic testing at companies and college campuses.
Combination tests are available that can test for COVID-19, seasonal flu and sometimes other respiratory infections.
Testing is trending toward faster results and convenience as seen by the more recent emergence of rapid antigen tests, saliva sampling and home-based testing.
To date, two molecular and one antigen home-based test have qualified for FDA EUAs. Because the quality of sample collection can affect accuracy, some products offer videos to help guide the process.
It is not yet known if/how virus variants will impact the efficacy of test results.

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