A lower Ct value means that there is more virus present in the specimen. If the virus is present in higher levels, it will take fewer amplification cycles to reach that cycle threshold. The ‘Cycle threshold’ or Ct value is the number of amplification cycles required to detect the first signal that the virus is present. During each cycle, the genetic material doubles in volume this continues until it is detected by the PCR device. The genetic material is copied in different rounds or ‘cycles’. That means that the test cannot give a positive result for other viruses, such as those that cause the flu or the common cold. This fragment of genetic material is specific to the SARS-CoV-2 virus. To ensure that the test will be as sensitive as possible, a specific fragment of the genetic material is amplified (copied) using the polymerase chain reaction method, known as PCR. That means that the PCR test also detects the virus in someone who has a low viral load, either because they are not carrying much of the virus yet, or they no longer have much virus left in their body. That is why the PCR test has a high test sensitivity. In the PCR test, a small fragment of genetic material inside the virus is replicated repeatedly, in order to detect the presence of the virus even in very small quantities. This sample goes to a laboratory, where research is done to check for the presence of the SARS-CoV-2 virus. To perform this test, a smear is taken from the nose and throat with a cotton swab. The PCR test detects specific fragments of genetic material from the coronavirus SARS-CoV-2. The polymerase chain reaction test or “PCR test”

Due to the testing technique, the tests in the NAAT category are generally more sensitive than the rapid antigen tests (which includes self-tests). The category of tests known as NAAT (Nucleic Acid Amplification Test) includes the PCR test, the TMA test and the LAMP test. Which types of COVID-19 tests are there, and what do they tell us? NAAT category Various types of tests have been used over the past few years to detect a SARS-CoV-2 infection.

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