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Antigen vs. Molecular Testing: Explained

Even if you have never taken a COVID-19 test before, you’ve likely heard of both testing types: antigen and molecular. If you are confused about the differences between these two testing methods, you are not alone.

 

The COVID-19 pandemic brought complex medical terminology into our everyday conversations, especially as at-home tests become more widely available. Even though at-home COVID-19 tests are meant to empower consumers to take charge of their health and wellness, they can bring some confusion with them too.

 

If you plan on testing at home for COVID-19, it is important to understand what kind of test you are taking, what the results mean, and how likely it is that you might receive either a false positive or a false negative.

In this article, we explain:

  • The purposes and uses of diagnostic tests, antigen tests, and antibody tests.
  • Why molecular testing offers the most accurate results when testing for COVID-19.
  • How molecular testing methods have brought traditional lab tests into the hands of consumers.

If you are looking for rapid, molecular COVID-19 tests, Lucira offers tests for at-home use, or Rx tests in bulk for healthcare providers. Be sure to visit our page on The Science Behind Lucira for more information about our testing accuracy.

 

Diagnostic Tests VS. Antibody Tests

Before we review the differences between antigen testing and molecular testing, it is important to know what distinguishes a diagnostic test from an antibody test.

 

Antibody Tests

According to the FDA, antibody tests look for antibodies in one’s immune system that are produced in response to SARS-CoV-2, the virus that causes COVID-19. Antibody tests cannot and should not be used to accurately diagnose an active COVID-19 infection.

Antibody test samples are taken by a doctor or other medical professional and require a finger stick or blood draw to run the test. These tests confirm the presence of antibodies in one’s blood, which can take several days or weeks to develop and appear on a test after one has come into contact with the virus. Being vaccinated for COVID-19 may also result in a positive antibody test.

Antibodies can be detected in the blood of those who have recovered from COVID-19, or those who have been vaccinated against COVID-19. For COVID-19 and many other diseases, antibodies wane or decrease over time. As the antibodies decrease, you may be more vulnerable to illness.

According to the CDC, the risk of reinfection is very low in the first 6 months following an infection, and the presence of antibodies shows increased resilience to emerging COVID-19 variants.

 

Diagnostic Tests

Diagnostic tests are meant to detect the presence of an active COVID-19 infection. The two types of diagnostic tests are molecular (including its most well-known subtype, PCR) and antigen.

 

Antigen Tests

Antigen tests work by looking for specific proteins on the surface of the SARS-CoV-2 virus. These tests usually include a piece of paper with a strip of antibodies that bind to a viral protein, or the ‘antigen.’

If enough of the viral protein is present in the liquid your swab was stirred into, they’ll collect on that antibody strip, and change its colors, indicating an active infection is present.

This is the same process used in most home pregnancy tests. Like home pregnancy tests, antigen tests produce fast results and are very inexpensive to produce. However, they often need to be confirmed with a more reliable testing method.

There also needs to be a significant amount of viral protein in the sample for an antigen test to find the virus. This is why false negatives are more common, especially early on in an infection, before viral levels in the body reach their peak.

 

Molecular Testing: Explained

Molecular is an umbrella term for tests that amplify genetic material. These tests are also referred to as nucleic acid amplification tests (NAAT). According to the CDC, a NAAT is designed to identify specific RNA (ribonucleic acid) sequences within the genetic material of the SARS-CoV-2 virus.

This amplification is the key to the advantage of molecular tests over antigen tests because it allows them to detect infection from far less virus in the sample, resulting in earlier detection and more accurate results.

Polymerase chain reaction (PCR) tests are the most common type of molecular test. PCR tests are very accurate and reliable at detecting an active COVID-19 infection, even from very small amounts of virus in the sample. PCR tests typically require expensive equipment and highly trained operators, which is why they are usually only available from a lab.

Lucira uses a newer approach called loop-mediated isothermal amplification, or LAMP. LAMP is also a polymerase chain reaction, but advancements in technology have allowed it to be done at a constant temperature and in fewer steps. With these new advancements, the test can be powered by 2 AA batteries and miniaturized to fit in the palm of your hand. Lucira is the first test to put the power of amplification in a rapid at-home test.

At-home, rapid molecular testing for COVID-19 is becoming widely available for individual and personal use, as well as broader scale testing for businesses and public sectors, providing the best of both worlds: the accuracy of PCR and the speed of rapid antigen tests.

 

Need Rapid, At-Home COVID Tests?

Start testing and stop worrying. You can empower yourself during the pandemic by taking testing into your own hands. With our accurate, at-home molecular testing, you can trust your results.

Lucira COVID-19 Test Kits are available for individual and personal use, and for enterprise. In just 30 minutes, with three simple steps, our easy-to-use tests give you the accurate results you need to make informed decisions for your health. To learn more about our testing accuracy, visit our Science Page.

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