Why have the number of virus tests taken each day suddenly shots up?

[Trumpety]

From the government dashboard, the number of virus tests conducted seem to have doubled in the last week (UK). What is driving this? Are they including the school kids taking LFT or something?

Yes, it's school testing.

I’d be interested to know too. Wonder if it is the surge testing they are doing in some area.

Yes, school LFD tests will be included. Over 4m secondary / sixth form age kids in England.

I think it's the lateral flows and then you take a normal test if the lateral flow shows a positive. So I think yes it is the schools
Of course this means infections rise which allows the Government justification to impose restrictions permanently

I’m surprised it includes school testing by as those tests are known not to be as accurate. Does it include all the people testing for work as well (nurses etc)?

Three million secondary students taking two tests a week is going to have an impact. There will doubtless be an uptick in cases too especially as there is no way to knock out false positives. But it doesn’t mean that the improvements have reversed.

@Trumpety

I’m surprised it includes school testing by as those tests are known not to be as accurate. Does it include all the people testing for work as well (nurses etc)?

I thought the lft result wasn't counted because of false positives

It’s school staff and families of school aged children who are all taking lateral flow tests
Every test has to be logged on the website

We’ve suddenly gained another testing station in our town - we had one where you could book if you had symptoms, and now we have one where they just grab people on the street & ask them if they want to get tested, even if no symptoms. I have to admit I cynically wondered whether it was to keep the numbers high.

Secondary school children.
School staff
Parents of school children (primary and secondary)
Our town has started offering LTF tests to anyone who works in the town centre.

They are not 'known to be inaccurate'.
On the government website it says they have a 'specifity of 99.9%'. That is pretty darn accurate.

Local Authorities have to open more testing stations before the end of this month too. And families of school children can get tests as well. So those and school testing will have a big impact.

@Midlifephoenix

They are not 'known to be inaccurate'. On the government website it says they have a 'specifity of 99.9%'. That is pretty darn accurate.

There are two sides to the “accuracy” of any test.

Specificity for LFTs is indeed high, so the number of false positives is (relatively) low.

Sensitivity is low though, so the number of false negatives is high.

@Midlifephoenix

They are not 'known to be inaccurate'. On the government website it says they have a 'specifity of 99.9%'. That is pretty darn accurate.

Let's be really clear here:

They are 'specific' - if you get a positive, you are extremely likely to have Covid (though at apopulation level, the false positive rate is an issue, because even at less than 1 in several thousand, with your average secondary doing 3000 tests over 2 weeks, there will be false positives).

They are NOT 'sensitive' - as a rough estimate based on different studies, when done by patients themselves or under the supervision of relatively untrained personnel (as opposed to when carried out by scientists at Porton Down), they detect 50% or so of the infections that would be detected by PCR. The way the government presents this is that the LFT tests detect those with high viral loads, who are most likely to be infectious. However, I don't think that the 'minimum viral load' in person A to be infectious to close contact B has been established, so I understand this is an assertion, not absolutely factual.

What the layman means by 'accurate' is probably the second - does it detect if you have Covid? - or a combination - does it give exactly the right answer, whether positive or negative - every time? The answer to both of those is 'not really'.

I thought that the government coronavirus dashboard with daily stats now shows lateral flow tests and results separately from PCR tests, also how many positive LFT results have been confirmed as positive via a subsequent PCR test.

However, I can't find that data now myself - am sure someone else will be able to!

coronavirus.data.gov.uk

Colds and viruses in schools and workplaces never stopped circulating. Those who remained home for work and school won't have had a good winter illness since late 2019 or early 2020 so they'll all be catching up on that now, thinking it's covid, and testing for symptoms.

if they want to get tested, even if no symptoms. I have to admit I cynically wondered whether it was to keep the numbers high.

Or, just possibly, find any pockets of infection, in order to stamp them out.

If they had done this from the start, imagine how different our lives would have been. There was nothing inevitable about the wide spread of this virus.

@JanFebAnyMonth

I thought that the government coronavirus dashboard with daily stats now shows lateral flow tests and results separately from PCR tests, also how many positive LFT results have been confirmed as positive via a subsequent PCR test.

However, I can't find that data now myself - am sure someone else will be able to!

coronavirus.data.gov.uk

Just need to select cases by Nation and then England.

I struggled to find it first time round.

Here - coronavirus.data.gov.uk/details/cases?areaType=nation&areaName=England

case type by test type, including confirmed and unconfirmed LFT.

Thanks @boys3 and @PatriciaHolm

I thought the lft result wasn't counted because of false positives

School testing sites count as official testing sites so all the LFT results from schools are counted in the figures.

LFTs done at home don't - any positive LFTs done at home need to be confirmed by a PCR from an official testing site.

So once these LFTs at schools are finished (only the first 3 are done in school, then LFTs are done at home) the figures will go back down again (presumably asymptomatic spread reduced also by school isolations).

I'm
In primary health care, and we have just started twice weekly testing if our staff. I think the whole of Scotland is the same ( in our field). That could also be part of the reason why testing has shot up.
I think this is the reason that we have had higher cases in Scotland this last week. Much more regular asymptomatic testing in general.

We need to watch the hospital admissions and deaths in next few. Weeks. That's the real test. Hopefully with the vaccine programme kicking in, this will still continue to fall

That's not correct @houndedbytheherd , LFT results done at home are supposed to be recorded on the NHS website and will consequently be counted in the figures.

Provided people bother to upload them....

@Beaniecats

I think it's the lateral flows and then you take a normal test if the lateral flow shows a positive. So I think yes it is the schools Of course this means infections rise which allows the Government justification to impose restrictions permanently

No it doesn't.

@JanFebAnyMonth

That's not correct *@houndedbytheherd* , LFT results done at home are supposed to be recorded on the NHS website and will consequently be counted in the figures.

Provided people bother to upload them....

Yes, it's correct that the results should be uploaded, although only positives are required to be uploaded.

But a home test won't count in the figures because it isn't an official testing site, whereas schools are official testing sites - which is why a subsequent negative PCR cannot overrule the positive school LFT - but a positive home test can be overruled by a negative PCR test.