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April 28, 2020

How does PCR/Nasal Swab Testing Work for Covid-19

With the country and the world thrown unexpectedly into crisis by covid-19, the general population is suddenly dealing with medical and epidemiological terms that had never previously been part of its day-to-day vocabulary. Whereas three months ago the average person knew nothing of the sub-classes of medical masks, now the shortage of n95 respirators is on everyone’s minds. People concern themselves with their state’s stock of ventilators the way they used to worry about having enough flour in the pantry. And coronavirus tests, in all their forms, are at the forefront of everyone’s minds, promising a return to some sort of normalcy before the vaunted vaccine finally arrives. But with all you have read about covid-19 testing, there is a good chance you still don’t know exactly how it works. As a provider of PCR/ nasal swab testing, we endeavor here to describe what the test is and how it determines if a person has the disease or not.

The Purpose of the Testing

Nasal swab tasting is meant to determine if a person has covid-19 in that moment. It cannot prove that a person had the disease previously and since recovered. To ascertain if the disease was previously present in a test subject, an antibody/serology test must be administered, and researchers continue to study just how reliable these antibody tests are. For the nasal swab testing, it is only the current presence of the disease that can be accounted for.

To complete this test, a sample is necessary from the person being tested. This sample is then checked for the DNA of the coronavirus.

How the Sample is Obtained

The first step of the testing process is to obtain a sample from the person. This is done by inserting a cotton swab deep inside the individual's nose and throat. The goal is to get a decent sample of sputum- the goo that we typically associate with coughing, sneezing, or spitting.

Lab Testing

Once a sputum sample is obtained, it is tested in the lab to determine if the virus is present or not. A chemical called a “lysis buffer” is mixed with a small portion of the sample, forcing the opening of the potentially-infected cells. The viral RNA is then extracted from these opened cells. It is the RNA that holds the virus’s genetic code.

The viral RNA is then placed inside an RT-PCR machine, which copies the genetic material and searches for the presence of the coronavirus among it. The long-form name of this incredible device is “real time reverse transcription–polymerase chain reaction machine,” and it uses nuclear-derived methods to find genetic material in samples.

Fluorescent probes are applied to the sample, searching for specific coronavirus genes in the material. Each probe searches for a different gene, so labs typically use a number of them to search for various known genes. When coronavirus genes are discovered, the machine activates the fluorescent lights to amplify the presence of the genes. This illumination is detected by the machine, which then relays the information to lab workers on the outside via a graph on a computer screen. A spike in the graph on the machine means the detection of many coronavirus genes in the sample, indicating that the person has the virus.

Benefits of the PCR/Nasal Swab Testing Method

This has proven to be an effective, efficient, and timely method of covid-19 testing. The entire process can be completed with the sample remaining in a single test tube. This lessens the possibility of contamination and makes for more reliable results. The time necessary for the results of a test to come in varies by laboratory and manufacturer, but are much faster than any other type of test. That is why the PCR testing continues to be the gold standard in the world of coronavirus tests.

Protecting yourself and your family against the threat of covid-19 requires a multi-pronged approach, of which testing is just one component. Families and individuals should be sure to practice intensive personal hygiene, with frequent hand washing and no touching of the face. People should monitor themselves and their loved ones for symptoms, and have their temperature taken regularly. And when testing becomes the best option, it is the PCR/nasal swab tests that are most effective. Now, if you are administered one of these tests, you will know exactly how it works.

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