How Testing Works for Covid 19

A modified form of PCR known as the quantified polymerase chain reaction is used for COVID-19 testing (qPCR). In order to assess the level of genetic information in a sample, this technique incorporates fluorescent dyes into the PCR process. Here, healthcare professionals count the genetic information from SARS-CoV-2.

Using a nasal wipe or saliva tube, healthcare professionals gather samples to be tested before moving on to the next step. The infection that causes COVID-19, SARS-CoV-2, employs RNA as its genetic information. Reverse transcription, which transforms the PCR from single-stranded RNA to double DNA, comes first. Then, the two strands of the DNA template are split apart. The SARS-CoV-2 coronavirus is the cause of COVID-19. There are 3 different types of testing to determine if someone has COVID-19:

  • SARS detection with nucleic acid assays: virus RNA (ribonucleic acid) of CoV-2
  • Rapid antigen tests (RATs) are used to find SARS virus antigen viral proteins: virus CoV-2
  • Tests for IgM and/or IgG antibodies towards SARS using serology: -CoV-2.

Identifying the SARS-Cov-2 Virus’s Existence

Rapid antigen testing and nucleic acid tests are two different types of tests that can identify the existence of the SARS-CoV-2 virus.


This COVID-19 test, also known as a molecular test, uses a laboratory procedure called reverse transcription polymerase reaction to find the virus’ genetic material (RT-PCR). A medical expert will take a fluid sample from the back of your nose by putting a long nasal wipe (nasopharyngeal swab) into the nostril.

A very short nasal swab or a shorter nasal wipe (mid-turbinate swab) can be used to gather a sample (anterior nares swab). A lengthy swab may occasionally be inserted into the back of the throat by a medical expert (oropharyngeal swab). Alternatively, you can spit into a syringe to collect a sample of saliva.

If examined on-site, results may be accessible in minutes. If transferred to an outside lab, results may take 1 to 3 days or longer in places where test processing takes longer. When properly conducted by a medical specialist, RT-PCR assays are quite accurate; however, the quick test may miss some cases.

Antigen Test

Viral proteins in the viruses are found using the COVID-19 assay. Some antigen tests can yield results within minutes. The fluid sample is collected using a lengthy nasal swab.  When procedures are followed, a positive antibodies test result is considered accurate. However, there is a higher likelihood of false-negative findings, making it possible to have the infection without exhibiting symptoms.

The medical professional might advise an RT-PCR check to confirm a null antigen test result, depending on the circumstances.

The COVID-19 viral, influenza A, and influenza B can all be detected simultaneously by an RT-PCR test known as the Flu SC2 Multi Assay (flu). All three viruses can be detected with just one sample. This might be useful when the flu is around.

Any of these diseases could still exist even though the test is negative. Accordingly, the testing procedure could involve more steps based on the symptoms, potential exposures, and clinical assessment of your clinician.

Testing For Exposure: Serology, Blood, or Antibody Test

Your immune response to SARS-CoV-2 has been evaluated if you’ve had a blood test, antibodies test, or serology test. A blood sample is used in this kind of test to look for particular immune proteins called antibodies.

These are located in the serum, the clear fluid that is left over after blood’s clotting factors and cells have already been eliminated. In reaction to infections, such as those caused by coronaviruses, our bodies produce antibodies. The most popular technique for identifying these antibodies is the ELISA assay.

Testing For Viral: Quick Antigen Test

These tests look for virus particles, or antigens, in a nasal swab sample. Compared to the PCR test, this form of test may identify an acute infection much more quickly and doesn’t require a specialized lab.

However, the likelihood of an incorrect result is higher. There are two types of inaccurate results. Either the test incorrectly indicates that a person afflicted with SARS-CoV-2 is disease free. Or the testing incorrectly indicates that a person who is in fact not infected is bearing the infection.

Testing For Infection: Finding the Genetic Component of the Virus

This test can determine whether you are currently infected by detecting small fragments of the virus. The mucus membranes of the nose and throat, where the pathogen may be developing or has been spitted up from the lungs, are sampled using swabs.

The genetic material, or RNA, of SARS-CoV-2, can be found using either isothermal amplified or IA, testing, or PCR assays. Both PCR and IA tests are sometimes known as DNA amplification technique, or NAAT, tests because RNA is composed of nucleic acids. The gold standard for NAAT testing is PCR analysis.

Blood Test

Serology tests are not reliable in indicating active infection. We produce antibodies to coronavirus while infected. But these antibodies can persist for a long time after the infection has subsided. Additionally, because the majority of serology tests are developed to find a specific kind of antibody that appears later in an infection, they are better at detecting past exposure.

These antibody tests cannot determine if a person is immune to contracting SARS-CoV-2 again. A different test assesses a person’s ability to block infections by the recombinant coronavirus. This test comes closer to determining whether they are protected.

What Do The COVID-19 PCR Test Findings Mean?

  • When the DNA in the sample matches the SARS-CoV-2 primers and the sequencing is amplified, producing millions of copies, a positive result is obtained. This indicates that the evidence is from an infectious person. It is unlikely that a sample will test positive if viral RNA is not detected because the primers only amplify the genetic information from the virus. A false positive is what is known if it does.
  • A negative result is obtained when there is no activation and the SARS-CoV-2 primer does not fit the genetic makeup of the sample. This indicates that there were no viruses in the sample.
  • When an individual is infected but the sample has insufficient viral genetic material for the PCR test to identify it, a false negative result is produced. This may occur soon after a person has been exposed. False positive outcomes are substantially less likely to occur than false negative results overall.

Read Also: How Does the PCR Test Covid Help You to Get Rid Of Covid 19?

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