We have some excellent laboratories in the UK but they have been under immense pressure to ramp up testing numbers. The more testing the more false positives from volume alone. But people under pressure are more likely to make errors too. 3 ways we have made the situation worse:
1. Testing ramped up from 100,000 in May to 304,415 PCR tests a day today. Even the best labs will have false positive results. Addenbrookes has calculated theirs at 44% by repeat testing. This excludes false positives due to cross contamination, cross reactivity, RNA shedding.
2. Higher error rates in summer were taken as true positives and testing was ramped up further in those labs. This put even more pressure on the labs with the high error rates. bbc.co.uk/news/health-54…
3. We now have a policy of stopping quality checks in the laboratories with the highest rates to embed all the problems.
Addenbrookes will have been very careful to minimise that false positive rate before publishing that paper. Faced with mass volumes and high pressure even their rate will be higher. Everyone's would.

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More from @ClareCraigPath

17 Oct
TAKING NEIL O’BRIEN MP SERIOUSLY - a thread
Firstly, I have nothing against @neildotobrien who I am sure is well intentioned but badly advised
The reason for going back to normal is because the epidemic has passed. It’s over. We are now in the midst of a false positive pseudo-epidemic. thelancet.com/journals/lanin…
Read 23 tweets
17 Oct
This looks scary. If you look at all deaths and compare to hospital admissions 10 days earlier things look like they're getting worse. There are four possible explanations for this: a) we have got worse at treating COVID over since the summer Image
b) people are dying at home of COVID now whereas before they died in hospital
c) in the summer there were false positive COVID 'cases' but now it's back and it's killing people again
d) something else ?
Let's repeat but differently. Instead of the 10 day lag til deaths let's look at the ratio of admissions and deaths on the same week. That looks much less scary. Image
Read 6 tweets
16 Oct
The vast majority of COVID deaths in England since July have been mislabelled false positive deaths. Here is the proof. This chart shows the number of tests carried out in hospitals in orange and the deaths in blue. THREAD Image
You will notice that the shape of the two curves are very similar. We can test this. The chart below demonstrates that since August 93% of the rise in deaths can be accounted for by the rise in the number of tests done in hospitals over the 28 days preceding. Image
I have never seen such a tight correlation in my career. Biology just isn’t like that. But there it is - 93%.
Read 28 tweets
15 Oct
Asymptomatic spread does not exist. Sure some people test positive and even have virus but they don't spread it. All papers showing asymptomatic transmission are from China. We are being played. It's the man dropping suddenly dead (with outstretched arms) video but for science.
Asymptomatic spread does not happen in flu either. ncbi.nlm.nih.gov/pmc/articles/P…
Can we please stop calling asymptomatic people with a positive PCR 'cases' unless they develop specific symptoms.
Read 4 tweets
15 Oct
Great study here of 6 care homes in London (selected because they had COVID outbreaks in spring). Very sensitive antibody testing. All have reached herd immunity. By July half of London care homes had had an outbreak. Why are we screening those ones?
Here's why we should not be screening those homes lockdownsceptics.org/the-problem-of…
Where COVID re-emerges, the best tools to protect the elderly are handwashing, cleanliness in general, keeping symptomatic staff and visitors away and vitamin D.
Read 5 tweets
12 Oct
What if we turned the question around? What would we see if students were all immune and we tested them through mass screening?
We would expect a small proportion to be symptomatic (after all the symptoms are common) but the majority would be asymptomatic.
We would not expect to see transmission to other age groups.
Read 6 tweets

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