What is CT Value in the SARS CoV-2 RT-PCR Test?

Read on to know more about RT-PCR and CT value.

What is RT-PCR Test?

RT-PCR is the short form of the Reverse Transcriptase Polymerase Chain Reaction, which is the most common type of test available. Amid the ongoing second wave of Coronavirus infection, a record break number of people are getting themselves tests of the COVID-19 infection.

RT-PCR test is performed by taking a swab sample from the infected person’s throat and nose. In the labs, the sample is then used to extract the viral RNA (ribonucleic acid). This RNA then undergoes the RT-PCR technique that creates the strands of viral DNA.

This DNA is then further run through PCR for few cycles till it reaches a detectable level. To the DNA they add a dye, and when it is sufficient, it synthesizes to change the colour. The dye is specific and will work for the SARS-CoV-2/COVID-19 DNA.

What is Cycle Threshold (CT) Value in the RT-PCR Test?

In the lab, the DNA strand goes through several PCR cycles till it replicates itself. CT value refers to the number of cycles that the DNA takes to reach a measurable level. Supposedly, if the DNA undergoes 15 PCR cycles before the dye was detected, then its CT value is 15.

Before the tests come out as positive or negative, it’s important to know that the limit for a positive RT-PCR test is 35 as per the ICMR and CDC, USA.

It implies that the COVID-19 test is positive if the DNA gets detected within 35 cycles, if it takes longer then it is considered negative.

This is because a higher viral load will provide more viral RNA per sample. In turn, this RNA will generate more DNA through RT-PCR. The more DNA present, the sooner it will be detected in the sample. Therefore, when reading the RT-PCR report you need to check whether the CT value is below or above 35. A lower value is positive for COVID-19 and a higher value is negative for the disease.

How Accurate is the RT-PCR Test for COVID-19?

The standard test that is used worldwide for COVID-19 is the RT-PCR test. However, due to new strains that test accuracy has become a matter of concern in the third UK mutant strain. In such cases, your doctor might recommend you to undergo a chest CT scan.

Here are some of the factors that can affect your RT-PCR Test Results:

Virology Lab/Human error
Inaccurate collection of sample
SWAB sample storage
The stage of the infection

If someone has COVID-9 symptoms like cough, fever, low oxygen levels, pneumonia, loss of sense of smell or taste, difficulty breathing diarrhea, followed by a positive RT-PCR test then it is a good indicator of the virus.

While it is important to get yourself tested, another step that you can take towards your safety is buying a health insurance cover for Coronavirus. You can buy affordable products like Corona kavach and corona Rakshak policies. Or even buy a separate COVID health plan from your insurer. Even though your existing health insurance plan would cover it, but it will not cover the cost of PPE kits, ventilators, masks, gloves, oximeters, that add-up to your COVID-19 hospital bills.

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Disclaimer: The list mentioned is according to the alphabetical order of the insurance companies. Policybazaar does not endorse, rate or recommend any particular insurer or insurance product offered by any insurer. For complete list of insurers in India refer to the Insurance Regulatory and Development Authority of India website www.irdai.gov.in