Which of the following statements is/are correct with reference to the ‘Ct value’ in RT-PCR tests?

Which of the following statements is/are correct with reference to the ‘Ct value’ in RT-PCR tests?

A. It is the gold standard for detection of the SARS-CoV-2 coronavirus.

B. It is the number of cycles at which fluorescence of the PCR product is detectable over and above the background signal.

C. Both A & B

D. None of these

Explanation:

Among various scientific terms that the Covid-19 pandemic has made part of the public vocabulary, one is the ‘Ct value’ in RT-PCR tests for determining whether a patient is positive for Covid-19. Short for cycle threshold, Ct is a value that emerges during RT-PCR tests, the gold standard for detection of the SARS-CoV-2 coronavirus. The Ct value refers to the number of cycles after which the virus can be detected. If a higher number of cycles is required, it implies that the virus went undetected when the number of cycles was lower.