All About CT Value in COVID-19 RT-PCR Test

  • 38 months ago
3 minute read.
All About CT Value in COVID-19  RT-PCR Test

Productive prediction of viral outbreaks such as COVID-19 has been difficult to detect by scientists and public health researchers, and is even more demanding during the second wave of Covid-19.The CT (Cycle Threshold) value in the RT-CPR test demonstrates the presence of coronavirus and states whether the individual is COVID-19 positive or not. Indian Council of Medical Research (ICMR) determined that patients with less than 35 CT values will be considered as COVID-19 positive whereas below this CT value will be considered as negative.

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What is CT Value in RT-PCR Test?

Cycle threshold or CT value is a semi-quantitative value that can widely categorize the viral genetic material concentration in an infected patient's sample with RT-PCR high, medium, or low. In general terms, it helps detect whether you're COVID-19 positive or negative.

  • Low CT: Refers to high viral load which is typically related to high infectivity risk.
  • High CT: Refers to low viral load i.e. technically related with a lower infectivity risk. In addition to an upper respiratory tract sample, the person with a high CT value demonstrates a high infection risk such as early infection, degraded sample, etc.

CT values can be flawed or may produce wrong reports. ICMR Director-General Prof Balram Bhargava once said in a letter that adding such values to each test report “is not advisable and is scientifically flawed”.

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The RT-PCR Test

RT-PCR (Reverse transcription-polymerase chain reaction) is a lab test technique utilized to detect the presence of certain genetic material by a biochemical procedure of amplification using enzymes. This is used to detect the SARS-CoV-2 coronavirus. The RNA is extracted from the patients using the swab. Later it is transformed into DNA to amplify. In the process of amplification, multiple copies of genetic material detect the virus easily. The number of CT values found during the RT-PCR test defines the final report of COVID-19. RT-PCR technique for Covid-19 detection is being widely used in India in the on-going vaccination drive in India.

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Correlation Between CT Value & Severity of Disease

Despite the fact that viral load is inversely related to CT value, it does not define the severity of the disease. A low CT value defines the higher viral load, but a patient still can be asymptomatic. Hence, according to the expert findings and reports, onset of symptoms is directly related to CT values than the severity of the disease.

In some cases, though, the high CT value has shown the high level of COVID-19 symptoms. Therefore, besides the CT value, in the RT-PCR test, many other elements are also considered to detect the infection.


The spread of coronavirus is a new threat to the world but is getting severe in India. It is important to understand that staying home and getting tested on time is the only key to save oneself and our loved ones. The Wellness Corner app provides a platform to book RT-PCR test @ home and consult with a doctor virtually (chat, audio, video) to guide you throughout the journey.

The biggest challenge then was to find a cure for the deadly coronavirus but the biggest challenge now is to unify people to get vaccinated. Don’t let the sleepless nights of our corona warriors go in vain. If you are eligible,  find the COVID-19 vaccination center near you and please get yourself vaccinated because there’s nothing more valuable than the life you are blessed with. Save the world from another mass destruction by saving yourself! #IndiaFightsCorona

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