As of 5th August 2021, there were 20,596 confirmed COVID-19 cases in Malaysia. It is really worrying to see such a high number. Although COVID-19 has existed for more than one year, no everyone really understands the meaning of the CT value on the swab test report. 

What Is CT Value?

It is "Cycle Threshold Value" in full. The COVID-19 virus is extremely small, which is only about one-tenth of the influenza virus. In order to examine the concentration of viral RNA, it is necessary to replicate specific genes through the Polymerase Chain Reaction (PCR) test multiple times.

If the concentration of viral RNA in the body of the person is high, a lower number of replications is needed to detect the virus, which means a relatively low CT value and it also represents the high infectivity of the virus. 

People who have been infected for a long time have a lower virus concentration in the body. a higher number of replications is needed in order to detect the viral RNA. In this case, the CT value is higher, but it also means that the infectivity of the virus is low.

Generally, the CT value will be higher in the pre-infection period. After 14 to 20 days of infection, the CT value gradually becomes higher. If it is above 30, it means that the infectivity is quite low. On the contrary, if it is lower than 20 to 25, the viral load is very high.

Why Does It Matter?

Based on the standards of the World Health Organization (WHO), the CT value of 35, indicating that the viral load in the body is low. This also shows that their infectious power is not high.

According to Ketua Pengarah Kesihatan Tan Sri Dr Noor Hisham Abdullah (as stated on October 16, 2020), a CT value of less than 40 is considered as a confirmed case, and a CT value higher than 40 is not considered a confirmed case.