COVID-19: What is RT-PCR, antigen test?

Hyderabad: The Second wave of COVID-19 overwhelms the whole population of the country. The people frequently come across terms like Antigen or RT-PCR test. They want to ask many questions about the efficacy of these test in detecting the COVID-19 virus but no medical expert is free to answer their questions and allay their fears. This article shall provide answers to their questions.

Is Nose Swab PCR Test accurate?

The nose swab PCR test for COVID-19 is the most accurate and reliable test for diagnosing COVID-19. A positive test means you likely have COVID-19. A negative test means you probably did not have COVID-19 at the time of the test.

Get tested if you have symptoms of COVID-19 or have been exposed to someone who tested positive for COVID-19.

What is a RT-PCR test?

A reverse transcription polymerase chain reaction (PCR) test is performed to detect genetic material from a specific organism, such as a virus. The test detects the presence of a virus if you are infected at the time of the test. The test could also detect fragments of virus even after you are no longer infected.

Who should get tested for COVID-19?

If you have symptoms of COVID-19. If you have been within six feet of someone for 15 minutes or more who has tested positive for Covid-19.

How does a COVID-19 PCR test work?

There are three key steps to the COVID-19 PCR test: 1) sample collection 2) extraction and
3) PCR.

Sample collection is done using a swab to collect respiratory material found in your nose. A swab contains a soft tip on a long, flexible stick that is inserted into your nose.

There are different types of nose swabs including nasal swabs that collect a sample immediately inside your nostrils and nasopharyngeal swabs that go further into the nasal cavity for collection.

Either type of swab is sufficient for collecting material for the COVID-19 PCR test.

After collection, the swab is sealed in a tube and then sent to a laboratory. When a laboratory technologist receives the sample, they perform a process called extraction, which isolates genetic material from the sample including genetic material from any virus that may be present.

The PCR step then uses special chemicals and a PCR machine, called a thermal cycler, which cause a reaction to occur that makes millions of copies of a small portion of the SARS-CoV-2 virus’s genetic material.

During this process, one of the chemicals produces a fluorescent light if SARS-CoV-2 is present in the sample. This fluorescent light is a “signal” that is detected by the PCR machine and special software is used to interpret the signal as a positive test result.

Results and follow-up

What do COVID-19 PCR test results mean?

A positive test result means that it is very likely that you have COVID-19. Most people have mild illness and can recover safely at home without medical care.

Contact your doctor or visit a hospital or health center if your symptoms get worse.

A negative test result means you probably didn’t have COVID-19 at the time you took your test.

However, it is possible to be infected with SARS-CoV-2 but not have enough virus in your body to be detected by the test. For example, this may happen if you recently became infected but you don’t have symptoms, yet or it could happen if you’ve had COVID-19 for more than a week before being tested. Keep in mind that a negative test doesn’t mean you are safe for any length of time. So follow SOPs like using face mask and social distancing and avoid going to public places unnecessarily.

If your test is positive, talk with your doctor stay home and separate yourself from others. If your test is negative, continue to take steps to protect yourself and others from getting COVID-19 by following SOPs.

How soon are results of a COVID-19 PCR test available?

You should receive the results of your test as early as 24 hours after sample collection, but sometime it can take a few days depending on how long it takes the sample to reach the laboratory and how many other samples are in the queue to be tested.

What are the advantages of a COVID-19 PCR test?

The main advantages of COVID-19 PCR test are its accuracy and reliability. It is the most accurate test available for COVID-19 detection.

Are there downsides to a COVID-19 PCR test?

Because the test is able to detect very small amounts of virus material, it can continue to detect fragments of SARS-CoV-2 virus even after you’ve recovered from COVID-19 and are no longer contagious. So you may continue to test positive if you have had COVID-19 in the distant past, even though you can’t spread the SARS-CoV-2 virus to others.

How does the COVID-19 PCR test compare with a Rapid Antigen test?

Antigen test: This test detects bits of proteins on the surface of the virus called antigens. Antigen tests are typically considered rapid, taking only 15 to 30 minutes but are less accurate than a PCR test.

Rapid antigen tests are most accurate when used within a few days of the start of your symptoms, which is when the largest amount of virus is present in your body. Because this test is not as accurate as a PCR test, if an antigen test is negative, you can undergo a PCR test to confirm the negative test result.

How do I find out where to get tested for COVID-19?

If you have symptoms of COVID-19 or have been exposed to people who have symptoms or have tested positive, you may want to be tested. First, talk with your doctor or visit a health center or hospital near you.

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