Earlier quoted context omitted.
That's unfortunately not the case. PCR false positives are a massive problem. Scientists liked to claim during COVID that PCR tests don't have false positive because they use an obscure definition that doesn't match how people normally use the term. I wrote about this problem back in 2020 when it started becoming apparent that the public health establishment wasn't attempting to stop or even measure COVID PCR test fa…
The subtitle of your Jul 2020 essay criticizing PCR tests is "Why COVID-19 is guaranteed to never end". But in fact, judging by confirmed (by PCR, or by other tests grounded in PCR as you say) COVID-19 deaths, the pandemic has ended--the daily count has decreased by a factor of ~50 from the peak. Does that not suggest to you that maybe you were wrong? It's not just the decrease in testing, since test positivity has d…
Where do you see that? Where I live that isn't the case and according to official data the pandemic has never ended:
https://www.covid19.admin.ch/en/epidemiologic/test?epiRelDev...
As recently as April the positivity ratio was as high as it was in December 2020 (~16%). I have no idea who these people are who get tested 10,000 times a week but they do.
Now, I don't think this is just due to false positives. It might be - my point was and still is that we can't ever know due to these logic problems - but it might also be that Omicron mutation rates have just settled down into a background pattern that these tests still pick up or something. With no real definition of what COVID is beyond test results this question is unanswerable.
> contamination has to come from a true positive sample; so this is a problem only when the true positivity is high.
So? FPs are a problem regardless of when they occur or why.
> Sloppy clerical work could result in any possible incorrect result, but you've presented no evidence that this is a significant problem in aggregate.
How could I? Governments were told by scientists that PCR testing has an FP rate of zero, so they just didn't build any processes to recognize the possibility or measure the error rate. I had direct experience of clerical errors twice, and we didn't get tested much. And that's in Switzerland which has a relatively strong culture of quality control and carefulness. During COVID there were many viral social media posts and videos where people did things like submit a swab that had never been used, or that was dipped in a puddle, or where they swabbed their dog, and got a positive result. There were also lab challenge studies which showed some labs failed badly (although others didn't). To me these things are good enough evidence that FPs were a real problem.
> a positive PCR test doesn't necessarily mean that a patient is infectious now, but it does mean that they are or were recently (weeks to months) infected ... perhaps they initially misinformed you; but no one with any background in molecular biology was confused here
You're supporting my points here. Nobody cares about detecting people who were infected months ago. Yet governments reacted to any positive test by assuming they were highly infectious and immediately forcibly quarantining the unlucky person who got it. Even when people said "yeah I had it weeks ago but am fine now", that counted for nothing, because the test was taken to be the gospel truth. Anyone who pointed out that this was nonsense got shouted down as a "denier" (see responses to that blog post, or even my comments here on this thread in 2023!).
> Your idea that the PCR test is simply assumed to be accurate is completely false ... good enough for many statistical purposes
Statistical purposes!? People were locked in hotel rooms for weeks on end on the basis of these tests, they were prevented from taking vacations no refunds allowed, they were fined, they were locked in their homes. The Swiss government had a web page that stated point blank that PCR tests had no false positives at all. If this assumption is completely false, how could someone appeal a false positive, in your jurisdiction? Because I'm sure it was impossible in mine.
> The public messaging was again pretty bad there
The public messaging came directly from scientists. Unless you think politicians had opinions on the accuracy of PCR tests predating the pandemic, of course. I even ended up arguing about this with an immunologist acquaintance who used PCR testing for his job, he was also under the impression that PCR tests couldn't have false positives and anyone who thought they could was the victim of misinformation. When I told him COVID tests used a Ct>40 though, he turned pale, suddenly lost his confidence and said they shouldn't be doing that.