What is Ct value in COVID-19 report and why is it necessary?

Amid the pandemic, people are now familiar with several scientific terms.  Now one such term that becomes a part of the public vocabulary is ‘Ct value’

It is indicated in RT-PCR tests which help to determine whether a patient is COVID-19 positive or not.

A Ct (cycle threshold) value in a COVID-19 test report refers to the number of cycles after which the virus can be detected.

The lower the Ct value, the higher the viral load in the body as the virus was spotted after fewer cycles. It is important as ICMR stated that a patient is considered COVID-19 positive if the Ct value is below 35.

An individual is considered Covid-19 negative, only if the CT value is 35 in the RT-PCR test. So, if the CT value is below 35 in the RT-PCR test, then the patient is positive.

Recently, the Maharashtra government had requested the Centre to reduce the cycle threshold (CT) value cut-off from 35 to 24 for positivity rate under the RT-PCR test. They had asked to reduce the CT value for a lesser number of patients who come under the positive category.

However, the ICMR has said lowering the Ct threshold parameter may lead to missing several infectious persons.