PCR Test: Guide 2021

PCR Test

Have you heard about the hype created by COVID-19  and the importance of the PCR test for the diagnosis of this virus? I’m sure you have.

PCR Test commonly also called Polymerase Chain Reaction is a test that detects genetic material from a specific organism, for instance, a virus.

This test detects the presence of a virus in your body, in case you are affected by the virus or it is present in your body. However, this test can also detect the fragments of the virus after the virus no longer is present in you.

What is a PCR test?

This test is also called molecular photocopying, the polymerase chain reaction is a fast, and inexpensive test that doctors use to amplify copy-small segments of DNA.

Without the PCR amplification, it is nearly impossible to study the isolated pieces of DNA, therefore, significant amounts of DNA are necessary for molecular and genetic analyses.

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Use of PCR Test

After amplification of the DNA of the virus, doctors and scientists can use os many different laboratory procedures.

For instance, most mapping techniques in Human Genome Project HGP rely on PCR.

The technique of PCR is also valuable in a number of laboratory and clinical techniques, including DNA fingerprint, detection of bacteria or viruses (particularly AIDS), and diagnosis of genetic disorders.

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Applications of PCR Test

PCR test through throatThere are various applications of PCR tests. These are:

  • Selective DNA Isolation
  • Amplifications and Quantification of DNA
  • Medical and Doagnostic Apllicatioons
  • Infectious Disease Applications

Let us discuss the applications step by step.

Selective DNA Isolation:

This allows the isolations of DNA fragments from genomic DNA by selective amplification of a specific region of DNA. This allows the analysis of DNA samples even from small amounts of starting material.

Other Application includes DNA sequencing to determine unknown PCR amplified sequence. The use of this test is for genetic fingerprinting which is a forensic technique to identify a person or organism by comparing experimental DNAs.

Amplification and Quantification of DNA:

Scientist uses PCR test to analyze extremely small amounts of sample size. This technique is often critical for forensic analysis.

Quantitative PCR or Real-time PCR allows the estimation of a given sequence present in a sample. This measures the accumulation of DNA product after each round of PCR amplification.

Medical and Diagnostic Application:

Prospective parents can get this test for genetic carriers or their children if a certain disease affects them.

Researchers collect the DNA samples by amniocentesis, chronic villus sampling, or by analysis of rare fetal cells circulating in the mother’s bloodstream.

PCR testing is also important where individual cells of a developing embryo are tested for mutations.

This test is also vital to organ transplantation. Many forms of cancer use this test to custom design the treatment plan for the patients.

PCR test allows the early diagnosis of malignant diseases such as leukemia and lymphomas.

Infectious Diseases: PCR test allows rapid and highly specific diagnosis of infectious diseases, even those whose cause a bacteria or viruses.

It allows the identification of non-cultivable or slow-growing micro-organisms such as mycobacteria, anaerobic bacteria, or viruses from tissue culture and animal models.

The application includes the detection of infectious agents and the discrimination of non-pathogenic from pathogenic strains by virtue of specific genes.

Testing and ApplicationCharacterization and detection of infectious diseases have changed in the following ways:

HIV and AIDS is a difficult strain to target and eradicate. However, antibodies do not appear early after the infection. PCR test detects as little as one genome among the DNA of 50,000 host cells, making the detection of this disease early.

PCR test allows the detection of small numbers of disease organisms in the case of Tuberculosis. An extensive analysis leads to immediate and effective therapy.

The detection of viral DNA can also be done by using this test. It can be used for the analysis, diagnosis of the DNA sequencing of the viral genome.

This permits virus detection soon after and even before the spread of the disease.

How it Works?

Researchers first heat the DNA dentures to amplify the segment of DNA using PCR or separates into two pieces of a single strand of DNA.

Afterward,  an enzyme, Taq polymerase synthesis builds two new strands of DNA, using the original strand as templates.

After making duplicate strands of the original DNA. then, each one that contains an old and a new strand creates new copies and so on.

Researchers repeat this cycle as many as 30 to 0 times leading to more than a billion exact copies of the original DNA segment.

After the automation and completion, researchers direct it towards thermocyclers in which at different temperatures, it allows the DNA to the denture and synthesize.

Covid-19 PCR Tests

With the outbreak of Covid 19 back in 2019, doctors used PCR tests to detect the existence of this virus in the human body.

To make sure the mass public health is either affected or not, doctors take antigen tests, PCR Tests, or RT-Pcr tests either at-home testing or at testing sites in Abu Dhabi.

The common Signs and Symptoms of COVID 19 are shortness of breath, fever, dry cough, and tiredness.

Moreover, a person might experience aches and pain, sore throat, diarrhea, conjunctivitis, headache, loss of taste or smell, etc.

Due to the presence of this virus, many people have come under the influence of it. it not only affected the men or elderly alone but pregnant women as well.

COVID-19 tests that most doctors recommend diagnostic tests like PCR test, antibody test, and RT_ PCR test. The implications and the results vary as you might get a positive result at the first attempt and get negative afterwords.

Therefore, they recommend you getting at least two tests that would identify whether you are suffering from COVID-19 or not.

COVID 19 Testing

Why is this Test Used? This test looks for the genetic material of the virus itself in the nose, throat, or other areas in the respiratory tract to determine whether there is an active infection with SARS- CoV-2

How is it Performed? A healthcare provider with use a swab and insert it into the patient’s nose or throat. It is then sent to the lab for testing.

COVID-19This test can also be done with Rapid Test in which the results are quickly available. This is usually done in the doctor’s office.

Results: A positive PCR test means that a person has the strain of the virus of COVID-19 in their body.

In such a case, you should isolate yourself for at least 10 days after the symptoms show. However, in case, there are no symptoms, you should still isolate yourself for 10 days.

In case the test results are negative, it means that there was no detection of the virus in your body. However, it does not rule out the fact that the virus is not present in your body rather it is not detectable at this stage.

Your doctor will advise you to isolate yourself and have another test, Rapid Antigen.

If the result of this test is also negative, then you can shorten the length of your isolation to 7 days.

Vaccination: After vaccination, you do not need to isolate yourself, however, you should meet the following criteria:

  • You have a complete course of vaccination following the receipt
  • You are asymptomatic since the current COVID-19 exposure.

After stopping the isolation, you should watch for the signs and symptoms of COVID-19.

However, if you have signs and symptoms immediately isolate yourself and contact your doctor or health care provider for assistance.

Use a mask and make sure to maintain a 6 feet distance from others. Wash your hands, avoid crowds and take steps to prevent the spread of Covid-19.

COVID-19 and Tests

Your doctor might recommend you get the diagnostic tests for COVID-19 if you are showing signs and symptoms of it.

For the tests of COVID 19, the tests are either done in the testing site or are done at-home testing.

Testing Site: It is a separate facility in a hospital or a building where the doctors take Antigen tests, PCR tests of COVID suspects.

At-home testing: Doctors might come to your home for at-home testing to either take a PCR test, antigen tests, or an RT-PCR test.

However, if you have just traveled from one country to another, then you definitely need to get the test done. These tests are as follow:

PCR Test: Also known as Polymerase Chain Reaction this test is done to diagnose the presence of COVID-19 virus in your body.

The benefit of using this test is that it can detect even the slightest presence of a virus in your body.

Healthcare professionals perform this test by using a swab into your nose or throat and then sending it to the lab for testing.

You can get the test results within 2-3 days.


Antibody Tests: Our immune system produces antibodies that fight bacteria and viruses. Antibodies are made of proteins.

These are present in our body when you are attacked by COVID-19. However, it can take up to 2-3 weeks to devel enough antibodies that are detectable in your blood.

these antibodies remain in our body even after we recover from COVID-19. Antibody test detects certain types of antibodies that our body produces to fight COVID-19.

  • Binding Antibodies: This test detects whether you have antibodies in response to COVID-19 infection. However, they do not indicate the extent of it.
  • Neutralizing Antibodies: This is a new and sensitive test that detects a subgroup of antibodies that may inactivate the virus. After you test positive for COVID-19, you can take this test.

RT-PCR: This is a widely used test that detects the presence of the COVID-19 virus in your body.

Your healthcare provider will collect the samples from parts of your body such as the nose or throat. They will then treat it with different chemicals in the lab to remove the substances such as proteins and fats.

This extracts the RNA. If the RNA of the virus is also present in your body then this means you are suffering from COVID-19

What is the Difference between Covid-19 Rapid and PCR Tests?

To contain the spread of COVID-29, testing has a great value. It can easily help identify the spread of this virus by making sure that it does not spread to others.

There are clear indications as to which test you should get and not some for clear reasons.

Rapid Test detects protein fragments specific to this virus. The turnaround time for results is quick and in some cases, it comes out in 15 minutes.

However, PCR Test detects the RNA strand specific to COVID-19 in many ways. This test actually detects the strands of virus in your body even when it is just new in your bloodstream.

Turnaround is longer and takes 2-3 days however results can be in as little as 24 hours.

How Should get a Rapid Test?

Rapid tests are more accurate in a person who is showing signs of fo COVID-19.

While the rapid test can get you results quickly the results, however, are not accurate and you might COVID-19 and rapid testneed to take the test again.

What does A False Negative or False Positive Mean?

The False-negative rate means that your test result is negative but you actually have the virus present in your body.

The chances can be as high as 50%. This can have great consequences as many doctors are trying to contain the virus from spreading.

The False-positive rate means that you do not have the virus in your body and the chances of its presence are very few.

However, if you do test positive from the rapid test, then you are more likely to have this disease in your body.

What If you Have A Negative Rapid Test but Still Have Symptoms?

Most doctors suggest that if you have symptoms and have a negative rapid test, you need to have a confirmation test.

High risk to exposure is more than 15 minutes of contact with a COVID-positive individual in a 24 Hour time frame and you have to be within 6 feet for the effect of this virus.

COVID-19 and Precautions

The transmission rate of COVID-19 is higher than other viruses as it can spread easily if you are within its range

Research suggests that it can spread from an infected person to another if the distance between them is less than 6 feet.

To avoid the spread of this virus, you person who is showing signs and symptoms of COVID-19 should not come in close contact with other people as close contact the major cause of spreading this disease.

Wash your hands and use tissue paper. Avoid contact with people within 6 feet and maintain distance.

you should stay in isolation for at least 14 days and if the signs and symptoms get worse, contact a doctor or health car provider as soon as possible.

Advantages of PCR Test

It is simple to understand and use and the results are rapid. However, this technique is highly sensitive with the potential to produce millions of copies of the specific product.

Researchers can use them for sequencing, cloning, and analysis. Therefore, it has uses to analyze alterations of gene expression levels in tumors, microbes, or other diseases.

Results of PCR TestMoreover, it is a powerful and practical tool. This technique can help identify the previous unknown viruses and thus gives us a better understanding of the disease itself.

By further simplification of the process and can develop sensitive non-radiometric detection systems, the PCR will assume a prominent place in the clinical laboratory for years to come.


In order to generate multiple DNA sequences, you must have the original primer for selective amplification.

This means, that you must know the precise sequence of the target region of each of the two strands.

DNA polymerase is prone to error just like all other enzymes. However, it can cause mutations in the PCR fragments.

Another limitation is you can even amplify the smallest DNA, which can result in misleading and ambiguous results.

However, to avoid chances of contamination you can create separate rooms for the analysis and reagent preparation.

Environmental samples that contain humic acids may also inhabit PCR amplification and lead to inaccurate results.

The Takeaway

Over the years and with advancements in technology, the PCR test, and its importance have increased.

The importance of the PCR tests is evident from the recent pandemic COVID-19. Doctors recommend PCR tests worldwide as they provide results within 2 or 3 days and they can easily detect the presence of virus even if it has a small number in your body.

The application of PCR is vast in medicine and science like forensic, genetics and heredity, cancer treatment and its planning, etc.



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