Using the correct test

[debbs77]

I only found this out this week......

Lateral flow tests are for use without symptoms

PCR tests are for use WITH symptoms.

So many people don't know this! And I think it is why so many think lateral flow tests are rubbish, because they often give false negatives when symptoms are present.

I had symptoms, had negatives for 3 days before I finally got a positive, confirmed by a PCR (Covid has swept through our household this last week)

I'm absolutely amazed people don't know this. I've heard so many people make this error in the last few weeks .

Then why would I have been allowed, via the Government's own website, to order a PCR test, when I didn't have any symptoms?

I had, though, been in close contact with someone who subsequently tested positive. Does that make a difference?

From the Government's website:

Getting a PCR test if you have no symptoms
You can also use this service if:

you’ve been in contact with someone who’s tested positive
you’ve been asked to get a test by a local council or someone from NHS Test and Trace
a GP or other health professional has asked you to get a test
you’re taking part in a government pilot project
you’ve been asked to get a test to confirm a positive result
you’ve received an unclear result and were told to get a second test
you need to get a test for someone you live with who has symptoms
you’re in the National Tactical Response Group

So it's not an error

Well that’s all well and good, but I am off work with a nasty cold, and cannot get a PCR test for love nor money. None available.

Lateral flow are more reliable when you do have symptoms. They have a high false negative rate if you don't have symptoms.

Nevertheless it's PCR you should use if you have covid symptoms

So I’m using the LF, which have been negative, and the pharmacy gives those out like sweets.

@SmidgenofaPigeon

Well that’s all well and good, but I am off work with a nasty cold, and cannot get a PCR test for love nor money. None available.

You can get one sent to you in the post. Mine came within 24 hours

No, I can’t @BIWI.

On the UGOV website, as soon as I tick the box to say I’m not a key worker, and then I don’t have the three main symptoms, (I don’t have a fever or a cough) I won’t be eligible unless I lie as to why I need it. So I guess I could try that but my point is, they’re not easy to get, and I don’t get paid to isolate while I wait for the results. Pretty sure I don’t have covid (as sure as I can be and neg LFs) but people don’t always take LFs because they’re mistaken, they’re just easy to get hold of.

Smidgeon can you not just tick that you have a fever and cough?

I had cold symptoms, no fever or cough and I took lft and negative. I feel so stupid and really irresponsible that I didn't know that I should of taken a pcr. I really don't know now if maybe I had covid I'm an idiot :(

@NigellaSeed I could, but the point is I don’t get paid to isolate while I wait, and since I don’t have the big three symptoms, and technically that means I’m not eligible for a test, it’s really easy to see why people just think oh well I’ll take a LF, it’s negative so let’s crack on.

Not saying you thought that, I don’t think you were stupid at all!! It’s the way it’s set up.

It is terrible that the original 3 symptoms are the ones still used to allow people access to tests!

We have had the Delta variant.....different symptoms altogether! One child just had a tummy ache!

@debbs77 yeah, I think it’s crazy it hasn’t been updated abd it’s still only the three retro-covid symptoms

Dsis went for an LFT when she had symptoms about 6 months ago. Negative. It was only when I pointed out that she'd taken the wrong test that she went for a PCR. Positive, all of her household quickly went down with it. Babies included.

I don't think that's true. My DS PCR for travel was positive day before symptoms, my LFT positive with symptoms. PCRs are more accurate, therefore if you've got symptoms you should use the more reliable test. That is all.

Lateral flow are more reliable when youdohave symptoms. They have a high false negative rate if you don't have symptoms.
@dementedpixie do you have a source for that as I don’t think that is right.
A school family all caught COVID . They all had symptoms and initially used LFTs which were negative. Subsequent PCRs positive.
I know false negatives are an issue with LFTs but thought they were designed for use without symptoms.

It's not that they only work if you don't have symptoms. It's that you are far more likely to have Covid if you have symptoms, so you should use a PCR to check. LFTs are meant for finding asymptomatic cases in the community that would otherwise be spreading Covid without realising.

But of course the government haven't made that clear, so everyone uses them for mild symptoms, gets a negative because they have a low viral load, and goes around spreading Covid merrily and we end up with 50k cases a day and rising.

My sons friend had no symptoms (double vaxed) but did a LFT for work and was positive, a clear line, but he did a second one to make sure, again positive. Still no symptoms but his employer asked him to get a PCR test, which he did and was negative so he ignored the LFT and went back to work/watch the football in the pub! In my mind the PCR may have been a false negative as he had no symptoms but the LFT was correct as thats what its intended for.

@Jenasaurus but you are wrong. LFT’s are for asymptomatic testing because they are NOWHERE near as accurate as a PCR test. The point of sending them out widespread into the community is that even if it picks up one asymptomatic case, that’s a positive. This article here explains it. LFT’s are more likely to give you a false result which is why and positive LFT is to be followed up with the more sensitive PCR test. So your sons friend was absolutely correct in his behaviour.
pharmaceutical-journal.com/article/feature/how-reliable-are-lateral-flow-covid-19-tests

[quote Pantene23]@Jenasaurus but you are wrong. LFT’s are for asymptomatic testing because they are NOWHERE near as accurate as a PCR test. The point of sending them out widespread into the community is that even if it picks up one asymptomatic case, that’s a positive. This article here explains it. LFT’s are more likely to give you a false result which is why and positive LFT is to be followed up with the more sensitive PCR test. So your sons friend was absolutely correct in his behaviour.
pharmaceutical-journal.com/article/feature/how-reliable-are-lateral-flow-covid-19-tests[/quote]
Thank you for that, so the PCR works for both symptomatic and Asymptomatic cases. That is reassuring as he was with me and my DS for the afternoon before he did the postive LFT test. :)

Yeah.....that's not right. LFTs aren't "for asymptomatic cases". LFTs will pick up infection with about a fifty-fifty accuracy regardless of whether you have symptoms or not. They're only supposed to be used for asymptomatic people because they're quite shit - so only really useful for picking out cases we otherwise would be oblivious to. PCR are more accurate - and again will work correctly regardless of symptoms - but are expensive and slow so they're only using them for people who have symptoms and there's good reason to think they have it.

This is about the third thread I've seen where someone thinks "LFTs test for asymptomatic cases" and "PCR tests for symptomatic cases". That's how we're advised to use them, but both tests identify infection regardless. I think we can agree that understanding of how they work is poor!!

LFTs don't give out false negatives when symptoms are present. They give out false negatives because they're rubbish.

It is terrible that the original 3 symptoms are the ones still used to allow people access to tests!

The same where I live. It's nuts.
And now people without vaccines are required to have certified rapid Ag tests (same as LFT) to access restaurants indoors. It means shit.
No wonder it's spreading!

The whole symptomatic/asymptomatic thing is a bit of a red herring. LFTs are a blunt instrument designed to survey large parts of the population & pick up some asymptomatic cases which would otherwise have been missed & be spreading Covid. In fact they are more likely to be accurate with symptoms than not because of higher viral load. It's not that they don't work if you are symptomatic. PCR tests are reserved for those with symptoms or a positive LFT as they are more accurate but expensive so can't be used to monitor the general population.