False Positives
The data continues to unfold exactly in line with a 0.17% false positive rate for the PCR test. Here's the chart. To recap: The definition of "false positive" is important to clarify. One type of false positive would involve detection of not only SARS-CoV-2 but other coronaviruses as well. Perhaps someone who has carefully studied the PCR primers and range of extant human coronavirus sequences could judge how likely this is to occur. A second type of false positive would be the detection of non-infectious viral fragments that can remain in one's respiratory passages for two-three months after the infection has been eliminated by the immune system. However, the class of false positives most people talk about entails contamination of PCR reactions with trace amounts of viral material – which in PCR labs almost always comes from previous reaction products. The PCR assay works by amplifying a few copies of virus molecules by millions or billions of fold, so it is pretty much impossible to completely avoid having some reaction products escape and contaminate the laboratory or some of the utilised reagents. These then get into, and become amplified in, subsequent test samples, causing false positive results. So let us call these "contamination positives". Since the PCR assays are performed in different laboratories in many places, contamination positives would cause ...
