Understanding COVID-19 PCR Swab Test

Polymerase Chain Reaction (PCR) test for COVID-19 is one of the most accurate and reliable tests for diagnosing COVID-19. 

What is COVID-19 PCR Swab Test?

COVID-19 PCR Swab test, or polymerase chain reaction test is a molecular test that analyzes the upper respiratory system for genetic materials of SARS-CoV-2, which is the virus that causes COVID-19. 

The genetic materials taken from your upper respiratory system will be amplified and to detect if SARS-CoV-2 is present in your body. The PCR test has been the gold standard for COVID-19 testing due to its high sensitivity and specificity.

When should you get your COVID-19 PCR Swab Test?

PCR swab test is mostly used for these applications:

Pre Departure COVID-19 PCR Swab Test

Most countries require travellers to do a Pre-Departure swab to ensure that they do not have COVID-19 before their flight, tests are usually done 48 to 72 hours before departure.

Confirmatory PCR Swab Test

A confirmatory PCR swab test is usually done when your Antigen Rapid Test results are positive or invalid to ensure that the results are accurate.

Voluntary PCR Swab Test 

You may request to take a COVID-19 polymerase chain reaction (PCR) swab test voluntarily if you are worried about contracting COVID-19.

How is the COVID-19 PCR Swab Test done?

There are three steps in the PCR swab test:

Sample Collection

A trained swabber will use a swab to collect respiratory samples found in your nose. After the collection is done, the swab will then be sealed in a tube and sent to the laboratory.

Extraction

When the laboratory receives the swab samples, they will isolate the genetic material from the sample.

PCR

A thermal cycler along with special chemicals and enzymes are used to amplify the amount of genetic material in the swab sample. After many cycles, a certain chemical in the tube will produce a fluorescent light if SARS-CoV-2 is present. The test machine is able to detect this for the laboratory to interpret it as a positive or negative result.

How accurate is the COVID-19 PCR Swab test compared to other tests?

There are currently two forms of COVID-19 tests, the PCR Test and Antigen Rapid Test

PCR Test

Test for the presence of SARS-CoV-2 genetic material. The most reliable and accurate test for detecting active infections and will take hours for the test to perform.

Antigen Rapid Test

Test of the presence of proteins (antigens). The test typically only needs 15 – 30 minutes for the results to be out. 

While the Antigen Rapid Test (ART) is much faster than the PCR swab test, it is less accurate. Therefore if your Antigen Rapid Test is positive, a confirmatory PCR swab test is needed to confirm the results.