At PentaBase, we apply Ct values as a method to determine if a sample is positive or negative in RT qPCR analyses of SARS-CoV-2. Here, you can read more about Ct values and RT qPCR analysis.
What does Ct value mean?
The Ct value is the cycle threshold; the value depends on the quality of samples taken during the period of sickness and the specific PCR method applied.
Regarding the detection of SARS-CoV-2, the Ct value is a value we apply to determine whether a SARS-CoV-2 sample is positive or negative and for quality control.
At PentaBase, we test on the three different SARS-CoV-2 genes: IP2, IP4, and E gene. Therefore, positive test results will show the Ct values for these three genes.
The RT qPCR analysis is the golden standard of SARS-CoV-2 detection and is considered the most precise method used in practice.
Research on Ct-values
RT qPCR analysis is the golden standard within the field of SARS-CoV-2 detection, and therefore, it is considered the most precise method used in practice.
At PentaBase, we use a Ct value cut-off point of 42 as other studies have demonstrated how individuals with low virus infection (high Ct values) still may transmit. (Read about the study here)
Other researchers have also documented that the Ct values should be interpreted with caution as results may differ using different testing machines and swab methods. Samples from the same person can give different results depending on the machine, sample quality, and sample method. (Read about the study here)