https://www.rcpjournals.org/content/clinmedicine/early/2020/11/26/clinmed.2020-0839.full.pdf
A very thoughtful team in Swansea systematically assessed the 31 positive PCR tests received through swabbing in summer 2020.
Despite the often rude comments from those who unaccountably insist false positives don’t occur & that I’m incorrect to keep...

...raising the topic, this study is a microcosm of the reality that FPs do occur & have very substantial adverse impacts.
31 positives out of 5,110 tests over a month. The FPR was 0.5%. 26 of these 31 positives were false, giving a False Diagnosis Rate of 26/31 or 84%.

You could adopt a more conservative position & say that, of the original 31 positives which were retested, 100% turned out to be false, for a FDR of 61%.

Note that if you don’t retest, you never learn which of the positives are genuine & which are false.

And we rarely retest.

This is why it is ESSENTIAL to know, routinely, in each of the small handful of large labs running U.K.’s PCR mass testing program, what the operational FPR is.

This value meshes with prevalence to yield the false diagnosis rate.

It’s fraudulent to pretend that the FPR is zero.

Note that this study was conducted at a time which predates the large Lighthouse Labs.
It shows that when prevalence is low, almost all the positives are false.
Those who’ve followed me for six months may recall that in the late summer, this is exactly what I said, that most...

...positives were false. I received much abuse. The data don’t care about opinions.

A few things. 9 of those found positive with single gene were symptomatic. Yet, of all those who were retested were negative. All false diagnoses, despite symptoms.

If this was today, all 31...

...people with a positive test would have to self-isolate, as would all of their contacts. However, at most, only 5 were positive using 2 or 3 genes, a more reliable testing method. Yet, of those, only 3 were symptomatic. Asymptomatic transmission is an unlikelihood. So if you...

...really using the best scientific approaches, only 3 out of the 5,110 people tested would need to asked to self isolate.

This tells us how is important is to know what are the characteristics of the PCR mass testing system who’s results are currently determining our lives.

I ask again, what is the operational false positive rate in each of the large, private labs (aka Lighthouse Labs)?
The data is this paper were generated by accredited staff & facilities such as NHS pathology labs. Even so, it has been shown that the majority of positives tests..

...were false.
It’s inconceivable that a huge increase in numbers of daily tests in non-accredited facilities, staffed at the swab sample processing step, by many people who’ve never worked professionally in a lab before, is associated with results as good as these.
Yet even...

...these results are problematic in terms of avoidable negative impacts on people & society.

I am unable to do any more than to demonstrate why the questions I’m asking are important.

I don’t believe that mass testing is necessary but if it must be done using PCR, the...

...conclusions from this work are:
1. Immediately retest all positives. This could enormously reduce “cases” & all the negative effects which are flowing right now from NOT retesting. It’s a low burden on the testing system because the % of tests which come back positive is...

...quite small. I can see no good arguments against this at all.
2. Test using two or three genes.
3. Regardless of the result, stop requiring asymptomatic cases to self isolate. The justification for this is woeful & should stop.