One minor quibble with an otherwise superb piece. Saying "100% false positives" maintains the idea that there is such a thing as a real positive, when as you point out a real SARS-CoV-2 virus was never physically isolated and purified so as to serve as a primer with which to calibrate the PCR test. Without calibration, any result of the…
One minor quibble with an otherwise superb piece. Saying "100% false positives" maintains the idea that there is such a thing as a real positive, when as you point out a real SARS-CoV-2 virus was never physically isolated and purified so as to serve as a primer with which to calibrate the PCR test. Without calibration, any result of the test is just plain meaningless, not capable of "false positives."
At Dartmouth, there was a real primer set for a properly sequenced DNA target, not requiring reverse transcription. The assay used at Dartmouth was designed correctly, so far as I know, to at least find the pertussis bacterium. We discuss this on the Mark Bailey interview. This was not the case of an in silico primer (such as SARS-CoV-2) which would indeed only get false positives as there are no true positives because there was no virus, a problem made worse by the use of reverse transcription for the fake "RNA" sequence they were looking for.
The lesson of Dartmouth was that even with sequenced primers designed to find the target, they could get 100% false positives.
Right. So this gets difficult to discuss in public discourse. The fact that PCR can repeatedly get 100% false even with real primers sets the bottom line. Where necessary or appropriate, I discuss the no true/false with SARS-CoV-2. But we don't have to go there right now...
There had been an early test from FDA for which they were excoriated for how it was distributed and the test was recalled because there were so few/new positives. No link. Sorry
One minor quibble with an otherwise superb piece. Saying "100% false positives" maintains the idea that there is such a thing as a real positive, when as you point out a real SARS-CoV-2 virus was never physically isolated and purified so as to serve as a primer with which to calibrate the PCR test. Without calibration, any result of the test is just plain meaningless, not capable of "false positives."
At Dartmouth, there was a real primer set for a properly sequenced DNA target, not requiring reverse transcription. The assay used at Dartmouth was designed correctly, so far as I know, to at least find the pertussis bacterium. We discuss this on the Mark Bailey interview. This was not the case of an in silico primer (such as SARS-CoV-2) which would indeed only get false positives as there are no true positives because there was no virus, a problem made worse by the use of reverse transcription for the fake "RNA" sequence they were looking for.
The lesson of Dartmouth was that even with sequenced primers designed to find the target, they could get 100% false positives.
True re Dartmouth, for sure. I was strictly speaking about SARS-CoV-2 and other in silico primers.
Right. So this gets difficult to discuss in public discourse. The fact that PCR can repeatedly get 100% false even with real primers sets the bottom line. Where necessary or appropriate, I discuss the no true/false with SARS-CoV-2. But we don't have to go there right now...
There had been an early test from FDA for which they were excoriated for how it was distributed and the test was recalled because there were so few/new positives. No link. Sorry