What is the point of Lateral Flow

[Blondie107]

I have heard that many employers are sending people to have Lateral Flow Tests every week or so. However doing more research I've learned that they have a 50% accuracy when done at home and not that much more when done at LFT centres. False positives are rare but there are lots of false negatives that mean the test has been unable to detect the virus

And then if it comes up positive you have to book a PCR straight away to "confirm" it which surely means that they know they're not reliable?

That’s interesting we’ve just tested 3 of us negative 1 positive. So waiting for the 2nd test to confirm so is it likely that that test will also be positive?
Is it usually that it’s false negative than false positive does anyone know ?
Obviously self isolating for 10 days but just curious how reliable the the lateral tests are .

@islockdownoveryet

That’s interesting we’ve just tested 3 of us negative 1 positive. So waiting for the 2nd test to confirm so is it likely that that test will also be positive? Is it usually that it’s false negative than false positive does anyone know ? Obviously self isolating for 10 days but just curious how reliable the the lateral tests are .

As further up, about 50%. False positive more likely than false negative.

So if the 2nd test comes back negative then I’m guessing you don’t need to isolate?

You do if anyone in your house has symptoms or if you develop them. Otherwise no.

@TomHardyAndMe

You do if anyone in your house has symptoms or if you develop them. Otherwise no.

Thanks .

False positive more likely than false negative.

Is that correct? I am no expert, but I had understood the opposite to be true.

Yes me too

Both my sons are in sixth form/school and they have to do LFT at home. They do the swabbing part but I do the bit that is the swishing in the tube whilst squeezing etc. I watched a few videos on how to get the best result possible.

When the test is complete I have to upload the QR code on the test to the NHS and then I have to upload the result to the school. They have put a sticker on it with a unique number for each child.

School has already had one asymptomatic child test positive in school and it feels like it is better than just winging it. I do feel that if parents have consented to the tests which initially took place in school then they should be trying their hardest to get an accurate result. Both my sons test twice a week on different days.

I can't comment about work places, Dh is currently working from home and I don't work.

I had a negative routine lft on Wednesday. Thursday evening I started to feel unwell so did another test which was positive. This meant I could contact co workers and managers there and then and confirm with a pcr the next day. It also meant that co workers who were feeling well tested and came back positive.
It meant that we could isolate quicker than if we had just waited for a pcr.

@AlexaShutUp

False positive more likely than false negative.

Is that correct? I am no expert, but I had understood the opposite to be true.

Yes sorry. Distracted whilst typing.

False positives are between 0.5 to 3 in 1000 depending on which study you look at.

False negatives are extremely common - roughly 50/50.

Everyone should know by now that if you have symptoms you do a PCR and totally ignore any LF results.

You only do an LCF if you have no symptoms.

It depends if the getting 50% of otherwise unknown cases outweighs the effects of the other 50% of people who "might" then go and be more liberal with the rules/ distancing etc because they think they are def covid free, probably yes so worth it.

It depends if the getting 50% of otherwise unknown cases outweighs the effects of the other 50% of people who "might" then go and be more liberal with the rules/ distancing etc because they think they are def covid free, probably yes so worth it.

Yeah, that's a fair point. I hadn't considered that some people might change their behaviour on the basis of a negative test. I hope most people wouldn't be stupid enough to do that, but who knows?!

The LF tests are supposed to be done twice a week - of someone is actually infected they will be infectious for about 10 days during which they will hopefully have 3 LF tests. If there's only a 50% detection rate then the infection will be detected at test #1 50% of the time, will be detected by either test#1 or test #2 75% of the time and by test#1 or test#2 or test #3 87.5% of the time - by doing the tests regularly it makes a huge difference to the overall success rate.

Oh have never seen it explained as clearly as that, thanks @KihoBebiluPute

For all those saying they catch asymptomatic cases - they don’t. It relies on people a) taking the test b) if it’s positive actually acting on it by isolating and having a pcr test.
Trouble is some cannot afford to off work and will work anyway, just reporting a negative result and some won’t want to take the test (for many reasons) and will still report a negative.
For the above, I mean those workers/students/households who do home lfts, not those taken at work by hcps

My dd pcr test came back positive so in my experience the lateral test is good as we wouldn’t have know and the whole household would of carried on as normal .