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Rapid vs Molecular Testing: Which is better and why?

Written by Geoffrey Trenkle, DO - Chief Medical Officer - Total Testing Solutions

Since the start of the pandemic, one of our greatest challenges as a nation has been access to testing. As the months have progressed, we have gained access to more types of testing. I wanted to write this blog to better explain all the different types of testing and introduce the newest type of testing available to us.

There are two major things that we must take into consideration when performing testing: Accuracy and Speed. While we want to get results as fast as possible, we also must be cognizant of accuracy. That word itself must be broken down to better understand what it means in the face of COVID-19 diagnostic testing.

Test accuracy is broken down into two categories. A test must accurately predict both positive and negative results. This is not as simple as it sounds. When describing testing you will often hear the words sensitivity and specificity. Sensitivity is the fraction of positive cases that the test correctly identifies as positive and Specificity is the fraction of negative cases that the test correctly identifies as positive. To make this more clear: 

  • A highly sensitive test will have a LOW FALSE NEGATIVE rate 
  • A highly specific test will have a LOW FALSE POSITIVE rate 

When doing diagnostic testing and screening testing, we want the test that is most SENSITIVE as it will decrease the chance of a false negative result (someone having the virus and us not detecting it). Specificity, or potential false-positive tests, seems scary but is only problematic in that it could cause people to quarantine when they do not need to. While this sounds bad, it is much more acceptable than the alternative. 

The second thing we must consider is speed. Speed is very often associated with the type of test performed. It is also closely related to accuracy. There are three major forms of testing: Molecular, antigen, and antibody testing. This can be further broken down into Diagnostic testing versus antibody testing. 

Diagnostic testing consists of molecular testing (most accurate) and antigen testing (fastest). A molecular test is used to identify the virus’s genetic material (DNA & RNA). This is the most accurate form of testing as it has the best sensitivity and specificity. Molecular testing consists of three major types right now. Reverse Transcriptase Polymerase Chain Reaction (RTPCR), Nucleic Acid Amplification test (NAAT), and Loop-Mediated Isothermal Amplification (LAMP). These tests are the most accurate as they identify viral RNA and/or DNA. The terms are often interchangeable. Antigen testing is another form of diagnostic testing that identifies the surface proteins of the virus. This testing can be done very rapidly (10 minutes) and in the point-of-care (no lab needed) setting but is less accurate (lower sensitivity and specificity).  

When it comes to diagnostic testing the goal is to find a test that is both accurate and rapid. To date, this test has been elusive and is one of the reasons why the virus has been so hard to contain. As new tests are coming out almost weekly, we are gaining more and more accessibility to screening for the virus in asymptomatic individuals. While RT-PCR will remain the gold standard for diagnostic testing, LAMP testing has the capability to bridge the gap between complex laboratory testing and antigen testing. LAMP testing can be done in the field and has been shown to be highly accurate (as accurate as RTPCR) and very fast (30 minutes).

As we continue to try and keep job sites safe, we feel the wave of the future will be LAMP testing as it provides high-level accuracy (comparable to RTPCR) with the speed of a rapid test.  

To learn more about LAMP testing and inquire click here

By Geoffrey Trenkle, DO - Chief Medical Officer - Total Testing Solutions 

Total Testing Solutions

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