The official guide for laboratory testing for coronavirus disease in suspected human cases by the WHO explains the procedure for testing a sample. On page two it states that the test
is based on detection for unique sequences of virus RNA by NAAT such as rRT-PCR with confirmation by nucleic acid sequencing when necessary.
As a layman I'm trying to understand how this works and specifically it this test involves the host's DNA or RNA. I understand that viruses attack and modify the host's DNA to get the host to make more copies of the virus.
Does the PCR test explained above target DNA/RNA of the host or does it attempt to find intact instances of SARS-CoV-2 RNA itself -- before it befalls a host's cell? It tries to identify the presence of the virus but does it do it on infected human genes or does it do it on the original virus?