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I think a lot of harm was done by early reports of LFTs as being really inaccurate that seem to have been repudiated now, but people still don't really trust them and think they might get false positives. I've heard more than one account of people with positive LFTs going out and about while waiting for their PCR to come back as presumably they don't really believe the LFT.
 
was the whole point of a lateral flow test not to show when you are current got a high load of the virus and are infectious

:hmm:

nah screw it after 10 days you are fine even if still showing a positive result

have I missed some thing
 
was the whole point of a lateral flow test not to show when you are current got a high load of the virus and are infectious

:hmm:

nah screw it after 10 days you are fine even if still showing a positive result

have I missed some thing
people can show positives way way after the ten days, in some cases months. i was speaking on the phone to the test and trace folks and they were saying that the main thing on day ten is a normal temperature. i explicitly asked them that if i was still testing positive to carry on isolating, and they said no as i was confused too.
 
I think a lot of harm was done by early reports of LFTs as being really inaccurate that seem to have been repudiated now, but people still don't really trust them and think they might get false positives. I've heard more than one account of people with positive LFTs going out and about while waiting for their PCR to come back as presumably they don't really believe the LFT.
They are inaccurate. The false negative rate is high. But the false positive rate is very low, so taking a positive result as “definitely got it” does make sense. Treating a negative result as “definitely don’t have it” is not such a good idea.
 
people can show positives way way after the ten days, in some cases months. i was speaking on the phone to the test and trace folks and they were saying that the main thing on day ten is a normal temperature. i explicitly asked them that if i was still testing positive to carry on isolating, and they said no as i was confused too.
So this is likely going to be me, post-Covid, completed 10 days of isolation, but still getting positive LFTs. How do you prove your safety to places that ask for a negative test - does your Covid pass automatically take into account your recent positive experience?
 
They are inaccurate. The false negative rate is high. But the false positive rate is very low, so taking a positive result as “definitely got it” does make sense. Treating a negative result as “definitely don’t have it” is not such a good idea.
I'm not saying they're super accurate, but I think they are more accurate than was initially highly publicised to the point where people don't take them seriously enough when they do get a positive.
 
They are inaccurate. The false negative rate is high. But the false positive rate is very low, so taking a positive result as “definitely got it” does make sense. Treating a negative result as “definitely don’t have it” is not such a good idea.
public understanding probably not helped by the large numbers of people who were (incorrectly) getting negative PCR results after a positive LFD result a few months ago.

question - if people are to be told to no longer get a PCR test, won't that affect detection of new variants? I thought that a random selection of PCRs were sampled for variants monitoring.
 
question - if people are to be told to no longer get a PCR test, won't that affect detection of new variants? I thought that a random selection of PCRs were sampled for variants monitoring.

There will still be plenty of positive PCR results for sampling.
 
Anyone been able to get an LFT pack in recent times? Every pharmacy around me is out and has been for a while. I need to get some as I have cold-type symptoms but nothing that qualifies for a PCR but need to travel and care for old people. Can't see much value in people diligently self-isolating if those of us unable to test are just wandering the streets infecting everyone around.
 
I wonder if they'll fall back on waste water sampling ...
Thats one of the ongoing ways they will continue to do overall infection rate surveillance even when the testing system becomes too stretched to give the same clarity of picture as it once could.

But obviously its not a direct replacement for some of the things they are using mass testing for, such as getting people to self-isolate.
 
question - if people are to be told to no longer get a PCR test, won't that affect detection of new variants? I thought that a random selection of PCRs were sampled for variants monitoring.
Yes, you are correct.

However since there is only so much capacity to do genomic tests on PCR swabs in the first place, the proportion of positive tests that are evaluated in this way already drops to a much lower fraction at times when the number of people testing positive becomes very large.

The other way they have been able to monitor for a particular new variant becoming dominant is to check PCR samples for S gene dropout, but since we'e already reached the point where Omicron is shown to be totally dominant using this method, such results are less important right now.

So you are correct to mention this issue, but the implications are of more concern if we are talking about the longer term, eg if they permanently change the PCR testing regime at some future point beyond the current Omicron wave.
 
The change is for people who've tested positive with no symptoms - previously the isolation period starts with the confirmatory PCR
Weird, test and trace gave 10 days fro symptoms appearance to my ex (her PCR was 5 days after the onset)
Anyone been able to get an LFT pack in recent times? Every pharmacy around me is out and has been for a while. I need to get some as I have cold-type symptoms but nothing that qualifies for a PCR but need to travel and care for old people. Can't see much value in people diligently self-isolating if those of us unable to test are just wandering the streets infecting everyone around.
I managed to order some online Monday morning, still waiting on delivery though.
 
Weird, test and trace gave 10 days fro symptoms appearance to my ex (her PCR was 5 days after the onset)
Yeah I think the existing guidance is slightly more complicated than I previously tended to think. I believe that if you initially test positive but dont have any symptoms, but then later symptoms begin, then they tend to start the 10 days from the symptom onset date. Thats just one example of nuance in the guidance, but it probably isnt evenly applied and there are different combinations of this stuff and the tests people end up taking.

I'll probably just wait till this latest change becomes official and then read the wording in official docs, and the final press reporting of this change.
 
Anyone been able to get an LFT pack in recent times? Every pharmacy around me is out and has been for a while. I need to get some as I have cold-type symptoms but nothing that qualifies for a PCR but need to travel and care for old people. Can't see much value in people diligently self-isolating if those of us unable to test are just wandering the streets infecting everyone around.
They seem to be improving - I last got some on NYD, but I've been seeing messages on kids' school whatsapp in the last few days saying when they're available and the gaps in supply seem to be getting shorter, like maybe half a day rather than vanishing for days on end.

I've decided I'm not going to have more than 2 ordered kits in the house at a time, otherwise it feels too hoardy considering we're a WFH household and no one is high risk or in regular contact with anyone at risk. Oldest gets one from school as well which I don't count in that, but obviously as a family of 4, and with youngest having to test twice a week (and not getting any from school) 2 kits don't last that long.
 
Sounds like the change to the testing regime isnt happening in England till January 11th, at leasts thats whats started to be reported.
 
Anyone been able to get an LFT pack in recent times? Every pharmacy around me is out and has been for a while. I need to get some as I have cold-type symptoms but nothing that qualifies for a PCR but need to travel and care for old people. Can't see much value in people diligently self-isolating if those of us unable to test are just wandering the streets infecting everyone around.

Maybe you should just get a PCR test if you can. I've seen the suggestion, I don't know how accurate, that right now the majority of people with cold symptoms will actually have covid.
 
Maybe you should just get a PCR test if you can. I've seen the suggestion, I don't know how accurate, that right now the majority of people with cold symptoms will actually have covid.

Yeah eventually I thought fuck it, I'll say I'm suffering one of the three symptoms that qualify for a PCR as this is ridiculous. However:

Screen Shot 2022-01-05 at 15.39.21.png

Which is rather like trying to order some LFTs:

Screen Shot 2022-01-05 at 12.12.49.png

So nothing. Nowhere. What a useless bunch of idiots these Tories are :snarl:
 
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I managed to order a pack of LFTs late on Monday afternoon for home delivery, and received them today. I still have a QR code from before Christmas to collect a pack locally but there are stlll none in the pharmacies here.
 
They are inaccurate. The false negative rate is high. But the false positive rate is very low, so taking a positive result as “definitely got it” does make sense. Treating a negative result as “definitely don’t have it” is not such a good idea.
I think thinking of them as inaccurate is unhelpful.

They pick up ~70% of asymptomatic positive cases, but are not sensitive enough to pick up more than that. Therefore, they shouldn't be used to give anyone the all clear, but should be used as an all stop/don't go out, if you get a positive. (I think you're coming from the same angle on that.)

In my mind, they'd be inaccurate if they routinely gave false positives, rather than not giving positives that they aren't sensitive enough to detect. In other words, they don't malfunction (more than any other test), but our/the generally communicated expectations of them are wrong.
 
The blighters tricked me a minute ago by suddenly enabling the Home Testing option again. What luck I thought! So I went ahead and filled in all the extra details I hadn't reached last time, but then was met, right at the final step, with the coup de grace:

Screen Shot 2022-01-05 at 18.19.11.png

:facepalm:
 
I think thinking of them as inaccurate is unhelpful.

They pick up ~70% of asymptomatic positive cases, but are not sensitive enough to pick up more than that. Therefore, they shouldn't be used to give anyone the all clear, but should be used as an all stop/don't go out, if you get a positive. (I think you're coming from the same angle on that.)

In my mind, they'd be inaccurate if they routinely gave false positives, rather than not giving positives that they aren't sensitive enough to detect. In other words, they don't malfunction (more than any other test), but our/the generally communicated expectations of them are wrong.
I think the issue has been in communicating something which is not simple black and white. The false negative and false positive rates are very different. There is a problem when people think a negative test means they definitely don’t have covid and use that info as a basis for doing a higher risk activity, eg visiting someone in the CEV bracket.
But it seems like it was too difficult to get across that they’re accurate in one direction and inaccurate in the other.

I think we’re saying the same thing tho 🙃😆
 
“The vagueness of this announcement is staggering. Once again the government is guilty of issuing confusing advice which creates worry and distress for potentially affected workers,” she said. “It rapidly needs to be made entirely clear which workers will or won’t be labelled as critical.”

 
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