Ds glaringly positive lft, pcr just came back negative

[Wagsandclaws]

So I started a thread yesterday about my two ds's who both had positive lateral flows. I booked a pcr and as suspected they came back during the night as negative.

What on earth is going on? Mine, Dh and dd lfts are still negative, these are from different batches too, I've attached this mornings and yesterday's from ds. They clearly have something - I can't understand why the pcrs aren't picking it up?

I've let the school know and sent them photos too. If people are being encouraged to take their children back to school on the basis of a negative pcr it's no wonder it's spreading the way it is.

I'm in the SW near Bristol. It isn't just this area though so I gather.

Wow they are very strong lateral flow! I would have expected positive PCR!

Maybe retest? Two people I know in the same family had this situation. They went back for a 2nd PCR and both came back positive.

There are a variety of explanations and you need to get into the prior probabilities to work out which is most likely.

To start with the bleeding obvious, is it likely that they could have faked them to get a day off school?

Assuming that's not the case, how much Covid is there in the school? Are they showing any symptoms?

False negative PCRs have always been a thing. False positive LFTs have also always been a thing. At 1% prevalence the odds are pretty finely balanced between the two possible explanations.

The higher the local Covid levels, the more likely it is that that they do have Covid and you should act accordingly unless the school is actually threatening you with fines.

I read in the news that this has happened to lots of people- how confusing!

Orange juice 😂

Anecdotally a postal PCR is less likely to produce a false negative so you could try that though obvs it'll take a couple more days.

There was a really good post on a thread at the weekend about why this would be. I’ll try and find it. Basically, it said to believe the lateral flow test!

It is this thread at
10/10/2021 18:20 post by GruntBaby

www.mumsnet.com/Talk/coronavirus/4371384-LF-test-and-PCR-test?pg=2#prettyPhoto

Were the tests done at a walk in centre? Are you sure the person who did them had the correct technique? The PCR definitely needs repeated.

There have been loads of casee like this in our school. A second or third PCR done 3-5 days later eventually comes through as positive in many cases.

If you can get out, it might be worth picking up a different box of tests and getting him to do one in front of you (without having eaten/drunk anything recently). Also, if you can get another PCR I'd do that, as those lines are very clear.

@EvilRingahBitch no they couldn't have faked them, I did them!

Yesterday's ones are from a different batch but they've all come up super bright and ds1's line showed up before the fluid has even spread all the way across the test.

Luckily my boys school don't expect them to come in even with the negative pcr - I have ordered a couple of 'at home' pcr's to get here on the next couple of days. I will do it again when they get here as I'm fairly certain they will turn positive eventually.

If myself, dd and Dh hadn't come up negative when both boys were so positive I'd have maybe thought there was something wrong with the batch but it's different batches and different results, the boys are symptomatic too. We aren't.

@Madmog they are 8 and 12 so I've been doing them, nasal swabs and I did the pcr yesterday too.

I think maybe the pcr is taking a while to turn positive as ds1 only started to show symptoms on Sunday afternoon.

This is happening to us too OP. My DS and I both have positive LFT - for three days running and from different batches of tests. We also have symptoms. PCRs came back negative.
We know we’ve had close contact with a positive person 7 days prior to us having positive LFT and also there is a high number of cases in the DS’s school. So probability of us having covid is high and we’re isolating because of that.
I’ve ordered repeat postal PCRs. We went to a test centre for the first ones.
We are also in the south west.

Your daughters test is positive too there. I'd rebook more pcr tests

The first LFT (labelled C) is also positive.

I haven't put her test up as it's completely negative.

The photos are of the boys tests from yesterday and today.

Ah sorry, I thought Cass was your daughter and the Ms were the boys!

The first pic has 3 positives though either way.

This is hers, not a hint of a line DH and mine are the same.

In this case does anyone know whether T&T date back the isolation period from your first positive lateral flow, or do they only count it from when you eventually get the positive PCR?

No Cass short for Caspar.

I can't see the point in doing pcr again when the lines are a strong as yesterday so maybe it takes a few days to turn positive as pauper have said on here anecdotally.

I've had a chat with the headteacher at the boys school and they have said to just stay home for 10 days from the start of symptoms regardless of whether the pcr we have ordered to do at home comes back negative or positive.

The trouble is a lot of schools aren't taking that approach and children with positive lfts but negative pcrs are going in especially if they don't have many symptoms.

** people not pauper 😬

@Wagsandclaws

No Cass short for Caspar.

I can't see the point in doing pcr again when the lines are a strong as yesterday so maybe it takes a few days to turn positive as pauper have said on here anecdotally.

I've had a chat with the headteacher at the boys school and they have said to just stay home for 10 days from the start of symptoms regardless of whether the pcr we have ordered to do at home comes back negative or positive.

The trouble is a lot of schools aren't taking that approach and children with positive lfts but negative pcrs are going in especially if they don't have many symptoms.

I would just isolate 10 days from symptoms and not bother with another PCR. But others might disagree.

It's worrying.

There have been quite a few threads on it and apparently it's 'being looked into' though gid only knows how long that will take and people will be spreading it believing they're negative...🙇🏻‍♀️

False positive LFTs are very rare. False negatives LFTs are common. It may be that they’re not infectious enough to trigger a positive PCR - that is one theory.

The local PHE team say if you have symptoms, a positive LFT and negative PCR you should isolate as normal.

@Iggly I read that false positives are really rare too.

The chances of 5 positives between the boys and none for the rest of the family are pretty much second to none.

I just can't understand what's going on with pcr's that they aren't picking this up or at the very least are taking days to 🤷‍♀️