Anyone with a positive PCR test 100% has SARS-CoV-2 RNA in their body and specifically at the test site (typically in the nasal cavity, but sometimes also at the back of the throat). That test will not come up positive for any other virus or bacteria. Not for a cold, not for the flu, and not for anything besides SARS-CoV-2.
The biggest problems with the PCR tests are 1) false negatives. If you get tested too quickly after infection, the swab may not be able to pick anything up. If that's the case, you can get a negative test (no COVID-19) and wind up testing positive days later. The other problem is that in some individuals who've had COVID-19, viral proteins remain present within the system for days or even weeks after the infection has been cleared. So the individual DOES have the genetic material present (thus a positive PCR test), but they are no longer dealing with an active infection (and thus are almost certainly not infectious).
But if you test positive, SARS-CoV-2 is present in your body.
“But if you test positive, SARS-CoV-2 is present in your body.”
False. The test picks up all kinds of other fragments. How was the system calibrated when, at the time the test was designed, there was not an isolated sample of covid19 available. Is there one now? Show us the proof.
Our local university does a saliva test on students. One of the football players tested positive with the saliva test and negative with the PCR test for next couple days.