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

How else would you describe it? You are not allowed to leave your house. It's not like lockdown when we were allowed out go for a walk or run or go to buy food (and shock horror Easter eggs and wine).

It does say they should determine the threshold based on the in-use assay. So perhaps different labs are using different assays and so you just can’t give one threshold for everywhere.

Choma might know more.

That page does seem to answer the criticism about false +ve due to ‘dead’ virus though. It would seem that is accounted for in both the NHS and commercial labs. So the retesting system already exists.

Perhaps that would explain some of the inconclusive results people get.

What is the alternative OP? I suppose retesting is an option but if youve got limited capacity its better to be testing more people than retesting.

If we are suggesting people go out because theres a chance they dont have covid, well equally they could have covid, are more likely to have covid. Then spread it and more people will need to do the dreaded 2 weeks house arrest?

I dont think this is as shocking as you think it is tbh. Before testing plenty of people isolated without covid? No one wants to isolate for 2 weeks but before testing lots of people did knowing full well it might not be covid?

It wont be repeat cycles of 2 weeks isolation because the actual chance of getting a false positive is still very low

David spiegelhalter was on the Today programme yesterday. This is the huge problem with mass testing in its current best case form. Far too many false positives affecting all your ‘contacts’ every time you eg are tested to go into a restaurant, theatre etc

Rafals I don't think they are retesting. Or do you think that's why it's back in 1 day for some and 5 days for others.

@DishRanAwayWithTheSpoon The chance of getting a false positive is low, but we are doing more and more tests a day so that increasingly impacts more people. And with the introduction of year group bubbles it is not just affecting said person plus 10 close contacts but 240 other children, who are missing crucial parts of their education. And their parents who may lose their jobs.
The way some people go on on here I actually think they would rather self isolators starve than take measured risks to get food for their families, or take early walks and time outside to ensure that their ASD child is not so distressed that they self harm or attack parents.

Figment, it is something that should be discussed openly. MH clearly knows its an issue, hence the request not to test with no symptoms. The info is buried. As is often the case.

Thanks @LearnedResponse. I am curious at how they got to 0.4% when there is no ‘gold standard’ test. So how do they distinguish between false positive and asymptomatic carrier? Is it whether they have any other contacts that test positive eg within 30 days?

Perhaps some machine learning algorithm might help reduce the rate of false positives? Perhaps we need some research - take multiple samples for a cohort and then calculate from there? Eg 3 out of 4 positive tests Taken over 2 different days equals a true positive and any less is a false positive?

I spent a lot of the pandemic in an East Asian country with v strict rules but v low death rate and excellent tracing. The number of cases they pick up each day is usually greater in asymptomatic people they test who are at great risk (people who live in dormitories of relatively high density) and people who are returning from abroad than in the wider community.

My brother did 2 weeks mandatory quarantine in a hotel room and was fine. He has no mental health problems though. He was provided with food and shelter - something our govt could arrange if it wants.

If I’m reading it correctly, the link you’ve posted is the guidance for restesting the samples that may have thrown up a ‘false positive’. It wouldn’t catch the false positive, but it would certainly deal with the shedding ‘dead’ virus issue that a previous poster linked to. It involves repeat testing of an existing sample or of another sample from the same patient.

And the request for asymptomatic people not to test unless they have been asked to was to do with capacity, not because MH thinks there is an issue with lots of false positives.

When people talk about mental health, we should also consider the mental health of people who are immuno compromised, who will have increased morbidity/mortality as cases rise and have already and probably will be asked to isolate and shield.

That’s not to say that other people do not have mental health conditions which should also be considered, but just that everything is a balance. Eg could a medical professional be able to certify that someone can do a 30min outside time due to severe MH/SEN issues? I doubt it would happen in this country, but this is possible.

It does say they should determine the threshold based on the in-use assay

I don't know about the specifics of the current tests - back when I did it, you just had to see if there was a band and you called it positive Things have moved on

However - good lab practise is to do External QA. You send the same sample to lots of labs - and see which ones report it as positive. I wonder how much QA is going on - it's been a very very rushed programme - and now lots of labs are involved.

I’m going to go out on a limb and say based on how well things have been handled so far, not a lot. And I’d say it’s probably better in NHS/PHE labs doing the pillar 1 testing. That’s based mainly on a rumour that some of the companies/labs that were given money to do the pillar 2 testing have limited experience.

I have no doubt at all that the pillar 2 testing us unreliable based on human error. I have heard of mix ups etc etc
I also don't think MH was basing it on capacity. Or certainly not of taking the swabs.
I am not sure what the solution is. But I'm pretty sure it's not forcing 240 children to spend two weeks under "house arrest" based on one potentially false positive. I've used the term house arrest as I do think it helps people realise that the restrictions are far more than lockdown was.
They are looking at ways of avoiding quarantine for those returning from flights abroad, perhaps they should focus first on avoiding children missing even more education than they already have. So perhaps testing on day 1 and day 5. (With repeats for positives to avoid any more false positives in the system. Incubation is only 14 days for absolute outlier cases (and I suspect these cases are where they actually caught it elsewhere...)
I don't get why people are so keen to just accept and not question what this government are doing. Especially when it harms their children's life chances for no actual benefit to others. (in the case of false positives)

"House arresr" Grow up OP.

Rosehip You are not allowed to leave your house for any reason. It is not actually too dissimilar. Although you haven't committed a crime. Anyway, I used the term as lots of people don't realise that you are not allowed to leave your house for any reason. No daily exercise etc etc.

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.

Yes, if there was SD in schools and masks this wouldn't be the case.

In Spain children over 6 wearing masks in school, lots of other countries too.

My daughter's school had half normal class sizes (less than 15), each class a bubble, and full SD for 4 weeks in June/July and no illnesses at all (with extra money, extra staff).

Loads of illnesses within a week now they're back with no SD at all, big bubbles because no extra money.

It's the fact that schools aren't even bothering with the same measures as everywhere else that's the bigger problem.

IloveJKrowling
Where is the evidence that masks help in schools? Spain are not doing very well and are hardly a shining light to hold up as reasons we should mask our children in the classroom.
Sweden are doing better. Much better. They have no masks. Including in the community.

There is lots of evidence that masks help everywhere else - why would that not apply in schools?

Anyway, there is evidence - the Israeli school outbreaks were after they abandoned mask wearing due to hot weather.

www.nytimes.com/2020/08/04/world/middleeast/coronavirus-israel-schools-reopen.html

Masks probably wouldn't matter so much if children weren't basically sitting touching each other in schools. When they have proper SD it matters less. To have neither - well, look at this forum, so many people saying their kids have been back at school a week and are sick with covid symptoms and can't get a test.

Treesofwood you do seem to have a bit of a bee in your bonnet regarding ‘house arrest’ and Covid in general. Are you on a mission?

Diplodocus A mission for what? Or for whom? I'm not a covid denier if that's what you mean. I've seen first hand how ill it can make people. Doesn't mean I have to agree with how it's being handled.

The problem for children is going to be the detrimental effect on their mental health if they are constantly in school for a few days, and then restricted to the house for 2 weeks; to my mind that is actually worse than online school but being allowed out for walks/exercise/meeting friends etc.

There are a lot of children already having to self-isolate at home, due to a positive test in their bubble; with large secondary school bubbles ( hundreds of children per bubble - often 200-300) there is a high chance of a child testing +ve at any given moment, and my fear for the children is that they will be paying a very high price of isolation at home for a few days in school.

Possible solutions; require 2 +ve tests? Make bubbles smaller (eg children do 1 week in, 1 week out which at least would halve the chance of them being affected by a +ve test). Revert to planned online teaching? Wait for 2 or 3 +ve tests in a bubble before isolating the bubble?

It is a very extreme position at the moment, and we wait to see if it will have a catastrophic effect on our children; my kids are right on the edge with their MH, so we are walking a bit of a tightrope I think.

Ilovejkrowling I can use Sweden as evidence for no masks if you can use Israel for wearing masks.

Wait for 2 or 3 +ve tests in a bubble before isolating the bubble
I didn't know before reading this thread that false positives were such an issue, the government/media mainly highlight the risk of false negatives.
But as someone with a DC in a bubble of 250ish, I don't like the fact that an arbitary figure of 1+v or 2+ve cases has been set, regardless of the size of the bubble. So in primary, that might be 3%of the 30 pupils, but in secondary it might less than 0.5% of the pupils. I feel the threshold should be consistent statistically. The current approach disproportionately disadvantages secondary/sixth form pupils. The equivalent of 2+ve cases in primary is actually 13+ve cases or more in a typical secondary bubble - sounds a lot, but it is the same statistically as in primary.

In Sweden they have small class sizes, therefore SD and I said it probably wasn't necessary to wear masks if SD in place.

Anyway a number of teachers have been ill and even died in Sweden so it's hardly an example of total success.

Bear in mind also, that many many people cannot get tests now. I know of a primary teacher who is off with what is probably a cold, but cannot get a test so has to stay off 2 weeks, and likewise children who are off with runny noses, NHS has said 'get a test', but there are no tests to be had.

So if a child who is at home can't get a test, there are 2 possible scenarios;

1. The child is negative, and is self isolating for 2 weeks entirely needlessly - bearing in mind that no online learning will take place because the teachers are teaching the rest of the bubble in school, so they may be entirely dependent on friends sending work home. This may happen EVERY TIME a child gets a cold or a sore throat.

2. The child is positive, but no test is available, so there is potentially continued spread through the bubble.

This whole situation is lunatic, and is massively detrimental to our children's education and well being. The plan for schools needs to be hugely changed, and the testing needs to be much more cleverly targeted.