The inventor of PCR is Kary Mullis has also done a lot of research on HIV. In this youtube he states that 'presence of a piece of RNA' does not mean 'sick or contagious'. RNA chunks can be present in our body for up to weeks. He also says that PCR is so powerful that a few molecules are enough to be amplified via PCR. Using PCR without the presence of clinical complaints is absolutely inadvisable

See wikipedia: https://en.wikipedia.org/wiki/Kary_Mullis