RT–PCR (Reverse transcription PCR) is essentially a variation of PCR (polymerase chain reaction). The two techniques use a similar process with one difference. RT–PCR has an additional step that involves reverse transcription or RT of RNA to DNA, to allow for amplification. Both techniques can be performed in real time. A look at the differences between standard PCR and RT-PCR:

Standard PCR:

• Uses a DNA template in the first stage
• Is used for pathogens such as bacteria and viruses that already contain DNA for amplification
• Is used for detecting viruses that cause diseases such as African swine fever, Ebola, and foot-and-mouth disease
• Is unable to measure the amount of DNA amplified 

RT-PCR:

• Uses an RNA template in the first stage
• Is used for pathogens containing RNA that needs to be transcribed to DNA for amplification
• Is used to detect COVID-19, which contains only RNA
• Is able to measure the amount of DNA amplified