False positives!-If we tested millions for the FLU "traces", what would be the result?-----How does coronavirus (COVID-19) nasal swab testing work? What actually happens during COVID-19 nasal swab testing? | MD Anderson Cancer Center

How does coronavirus (COVID-19) nasal swab testing work? What actually happens during COVID-19 nasal swab testing? | MD Anderson Cancer Center
"It looks for traces of the coronavirus’ genetic material, which is what makes a virus do what it does.

In the lab, we can prove a PCR assay can detect very small amounts of the coronavirus. 
But when we move out into the real world, things get a little more complicated.
The two main issues we’ve run into deal with specimen quality and viral load, or how much coronavirus is present in the body...Read all.