During an RT-PCR test: A sample is collected, usually from the nose or throat using a swab. The collected sample is then processed in a laboratory. In the laboratory, the RNA from the virus (if present) is converted into complementary DNA (cDNA) through a process called reverse transcription (RT). The cDNA is then amplified using the Polymerase Chain Reaction (PCR) technique to make many copies of the viral genetic material for easy detection. The presence of the virus in the sample is determined by analyzing the amplified DNA. The results are then interpreted to determine if the person is infected with the virus or not. RT-PCR tests are commonly used to diagnose infections like COVID-19 and are considered one of the most accurate methods for detecting viral RNA in a patient's sample.