Diagnostic COVID-19 Testing: Molecular and Antigen Tests

As of mid-November 2020, over 1 million people in the United States are being tested for COVID-19 every day.1 However, all COVID-19 tests are not created equal. COVID-19 tests vary in how the sample is taken, how quickly you can get results, what they test for, and the accuracy of the results.2 It’s important to know the differences in types of COVID-19 tests so you can make informed decisions about your own COVID-19 testing. 

There are two general categories of COVID-19 testing: diagnostic and antibody testing. Diagnostic tests show if you have a current, active case of COVID-19, while antibody tests indicate if you’ve been infected by COVID-19 in the past.2 In this blog, we will get into more detail on one of these categories: diagnostic COVID-19 testing. 

A doctor in a protective suit taking a nasal swab from a person to test for possible coronavirus infection

Diagnostic COVID-19 Tests 

As mentioned above, diagnostic tests tell you if you have an active COVID-19 diagnosis. Two types of COVID-19 tests fall under the category of diagnostic testing: molecular tests and antigen tests.2 Both of these tests typically use a nasal or throat swab. However, molecular and antigen tests differ in 1) which part of the COVID-19 virus particle they detect; 2) how quickly you will get results; 3) whether the sample is sent to a laboratory or handled completely at the patient care setting (i.e., “point-of-care”); and 4) the accuracy of the results. First, we will discuss molecular tests, which are the current gold standard for COVID-19 testing.3

Molecular COVID-19 Tests

  • Category: Diagnostic test
  • Includes: PCR tests, LAMP tests, and NAAT tests
  • Testing method: Nasal or nasopharyngeal swab
  • Detects: Viral genetic material 
  • Turn-around time: <1 day – 1 week 
  • Point-of-care: Typically, the sample must be sent to a laboratory for testing.
  • Accuracy: Very accurate (highly sensitive and highly specific)

Antigen COVID-19 Tests

  • Category: Diagnostic test
  • Testing method: Nasal or nasopharyngeal swab
  • Detects: Protein(s) in a virus particle
  • Turn-around time: <1 hour
  • Point-of-care: Testing is started and finished in the patient care setting (e.g., doctor’s office).
  • Accuracy: Less accurate than molecular tests, but still helpful. Positive test results are considered very accurate, but false negatives may occur in up to 20% of tests. For this reason, many experts suggest that if you receive a negative antigen test result, you confirm with a molecular test.


Need to know if you have COVID-19 right now? You need a diagnostic COVID-19 test! Antigen tests are generally quicker and cheaper, but less accurate than molecular tests. If your testing needs aren’t as time-sensitive (e.g., if you just need results in the next week), molecular tests are the way to go.





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