This paper used by Sage suggested 400 of 1600 positives were false. Still happy to have your school child home under house arrest for two weeks?

[Treesofwood]

Big problem with false positive us unnecessary self isolation for the person rested. Now it can lead to 300 children also being asked to self isolate for 2 weeks. This paper suggests when numbers are low, which they are at the moment, falso positives are a big problem. The more we test, the more we find them. www.gov.uk/government/publications/gos-impact-of-false-positives-and-negatives-3-june-2020
And the more children miss education and even being allowed to breathe fresh air if other threads on here are something to go by.
Obviously this is not a peer reviewed paper, but it is of enough interest and reliability to be used by Sage. Interested to hear thoughts, including if I have actually totally misinterpreted it.

It's not house arrest. Don't be stupid.

It's not much different if you actually follow it. But semantics aside, are you happy to self isolate with such a high false positive rate?

I would'nt worry about that 25% cases are false neg so all those kids are out at school spreading it.

Anyway worst case scenario all the false positive who have symptoms are having to stay home and not spread non covid bug which may save some kids having to be off

There can be 300 kids self isolating if one bubble "bursts". They are not allowed to leave their house or flat AT ALL. They miss education, socialising, exercising. It is a big deal. Especially if 400 of 1600 positives are false! 4000 contacts could easily be implicated if school cases.

House arrest 🙄 bit dramatic.

Daisydoo Please explain the difference between the two? If anything being on a tag is better. At least you can get out for some exercise and see people.

@Keepdistance

I would'nt worry about that 25% cases are false neg so all those kids are out at school spreading it.

Anyway worst case scenario all the false positive who have symptoms are having to stay home and not spread non covid bug which may save some kids having to be off

Or worst case scenario a false positive result causes a whole school bubble to self isolate, so multiple children without symptoms in isolation because they falsely believe they’ve been in contact with a positive case.

I'm fine with it

I do wonder what kind of QA and QC programme is going on.

RT-PCR is easily open to cross contamination. I've done lots of RT-PCR (although it was a long time ago) and it doesn't take much to get some RNA that can be easily amplified up. I would hope that steps are taken to ensure that suitable QA and QC takes place.

I would hope that positive patients are followed up - with maybe a repeat test and also antibody tests. Just to confirm the result

I am concerned that there seems to be a very low number of positive results compared to the number of tests taken.

These are supposed to be ill patients with suspected Covid -19 - yet many 1 - 2% of the results are positive.

The penny hasn't dropped yet for people

It's not a two week stint. It's two weeks inside 24/7, two or three weeks at school, 2 weeks inside 24/7, a few more weeks at school. Rinse. Repeat.

And don't get started on 'mass screening' of a generally well population - when there is a very very very good chance that your positive result with a lateral flow test to see if you are allowed entry is actually negative - but you are testing a well population with a test that is not 100% specific.

Premierinn And often for nothing. As so many false positives. So no benefit to self or community.

Chomaluanga, exactly up to 10000 false positives a day!!

@PremierInn

The penny hasn't dropped yet for people

It's not a two week stint. It's two weeks inside 24/7, two or three weeks at school, 2 weeks inside 24/7, a few more weeks at school. Rinse. Repeat.

Which is why we need to do what New Zealand and Australia did. So that we can get back to a normal life. It's better late than never.

Re tests. We also get false negatives.

The thing about many lab tests is that you just have to look for say a molecule, an antibody etc. It's there or it's not there.

With RT-PCR, you are finding the RNA and then amplifying it up loads so you can actually detect it.

That's an issue. Because any small bit of contamination is easily amplified.

OP, have you included the wrong link? The paper you've linked to says that the UK false positive rate is unknown.

Sheepandcow Do you honestly think with the number of ports, airports, train links that we can cut ourselves off from the world on the same way as NZ? That's without the population, population density etc.

Which is why we need to do what New Zealand and Australia did. So that we can get back to a normal life. It's better late than never

Just wondering, who are you campaigning about switching the overall policy to one like NZ and Australia? Your MP?
Or are you just telling MN that that’s what we need to do?

The paper you've linked to says that the UK false positive rate is unknown

True - but if it was say 99.6% specific (under perfect lab conditions), that means that out of every 1000 tests that were negative, 4 would be positive. Multiply that to 100,000 negative tests and 400 would be false positive.

And that's under perfect lab conditions. Not based on swabs done at home, with lots and lots of tests being done in busy labs.

Lilypond No, they hypothesised from what was known as between 0.4 and 0.8 and worked on an assumption of the lowest at 0.4.
I suspect this is actually lower than the real rate.

Why not? It's entirely within our control. As an island it's very easy.

Higher population density. Yes exactly. The ease of spread in a high density population makes taking effective action even more important.

I’m not sure how false negatives are relevant. It’s not like the one cancels out the other.

I’m not sure how false negatives are relevant. It’s not like the one cancels out the other

Separate issue - people falsely reassured. Who then pass it on.

(Relevant to this discussion I mean)

Exactly what I mean chomalungma