What is PCR and how is it different from real time RT–PCR?
RT–PCR is a variation of PCR, or polymerase chain reaction. The two techniques use the same process except that RT–PCR has an added step of reverse transcription of RNA to DNA, or RT, to allow for amplification. This means PCR is used for pathogens, such as viruses and bacteria, that already contain DNA for amplification, while RT–PCR is used for those containing RNA that needs to be transcribed to DNA for amplification. Both techniques can be performed in ‘real time’, which means results are visible almost immediately, while when used ‘conventionally’, results are only visible at the end of the reaction.
https://www.iaea.org/newscenter/news/how-is-the-covid-19-virus-detected-using-real-time-rt-pcr
Corona viruses have a single RNA, and need to be reverse transcribed first, to create a DNA needed for amplification. Hence for COVID test to have any meaning, it would need to be RT-PCR and not PCR only.