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Original poster

Can a strong positive on LFT ever be a false positive?

29 replies

AbstractEim · 22/10/2021 11:13

Anyone had an LFT look like this but tested negative on PCR? Are false positives ever this dark? Lines came up within 5-10mins. Am not hopeful but my dc are! It’s half term next week, and Halloween next weekend, they think there’s a chance it’s a false positive…they wouldn’t mind missing school, don’t want to miss holidays!

Can a strong positive on LFT ever be a false positive?
OP posts:
Shitfuckcommaetc · 22/10/2021 11:15

We just had a falsile positive, but the rest line was very, very faint

PurpleDaisies · 22/10/2021 11:15

I highly doubt it. You’ve got covid. Hopefully it’ll be a mild course.

Rubbish timing Flowers

girlmom21 · 22/10/2021 11:16

Get a PCR done but I'd be incredibly surprised if that's a false positive.

zaffa · 22/10/2021 11:16

The following are all apparently false positives for me (three PCR tests tell me I am negative)

Can a strong positive on LFT ever be a false positive?
Can a strong positive on LFT ever be a false positive?
Can a strong positive on LFT ever be a false positive?
bizboz · 22/10/2021 11:16

Highly unlikely. LFTs are less sensitive than PCRs so if you are showing a strong result quickly it is almost certainly Covid. My DC's was fainter than that on LFT and was a positive on PCR test.

Whiterose23 · 22/10/2021 11:19

That looks exactly like my eldest daughters test.
Youngest daughter’s was much fainter but both have tested positive on a PCR.
A cancelled holiday and half term in isolation for us.
I hope you’re feeling ok and remain well.

Brightmagic2021 · 22/10/2021 11:20

Very unlikely.

Noorandapples · 22/10/2021 11:21

Should probably take it as positive and order another PCR. I've had 5 days of positive LFT and a negative PCR, it's happening a bit in the South of England at the moment.

PurpleDaisies · 22/10/2021 11:23

@Noorandapples

Should probably take it as positive and order another PCR. I've had 5 days of positive LFT and a negative PCR, it's happening a bit in the South of England at the moment.
It happened became a lab totally screwed up and told 43,000 people their positive PCR was negative. We’ve effectively had a super spreader event in the south west.
BobLemon · 22/10/2021 11:26

It’s positive. For the sake of your DCs, lay it down ASAP and bloody firmly that it’s Covid and isolation has started.

mamatro · 22/10/2021 11:32

I tested positive on LFTs for a week yet 3 negative PCRs, non of mine were ever that dark though! Hope you are all ok x

TreeLawney · 22/10/2021 12:01

How rubbish :( I’m sorry you’re going to be stuck with isolation over half term. It truly sucks

Original poster
AbstractEim · 22/10/2021 12:57

Have been for PCR this morning, I’m pretty certain it’s gonna be a positive and am busy cancelling half term plans. It was one of the LFTs where you read the result between 15 and 30mins, the lines were dark before 10mins. Will update when PCR comes back

OP posts:
Original poster
AbstractEim · 22/10/2021 13:36

Found a different type of LFT, the one you wait 30mins so just done that one as well, before I cancel all plans and this line is even darker. Came up in seconds before the control line even appeared. Think that’s it for our half term.

Can a strong positive on LFT ever be a false positive?
OP posts:
mamatro · 22/10/2021 14:05

Ahh I'd say highly likely to be a positive PCR! Get stocked up on essentials and goodies and rest.. fingers crossed for you though

Wagsandclaws · 22/10/2021 14:12

This is what happened to us. Just out of isolation today ...

BlibBlabBlob · 22/10/2021 15:34

With those test results, if the PCR is negative then I wouldn't feel confident in believing it... seems like very strong results to me and you are likely to currently be very infectious. Sorry. :-(

CosmicComfort · 22/10/2021 15:43

Ds2 had the same strong LFT positive, PCR was positive the next day.

DH and I are currently negative with LFT’s and PCR. Day 5 of isolation.

Until DS2’s I’d only ever seen faint lines on LFT’s so was quite shocked by how dark it was.

Yellowmellow2 · 22/10/2021 16:45

You certainly have it. False positives are rare on LFTs so to have two positives, that’s fairly conclusive. Happened to me. Four positive LFs, symptoms, and two negative PCRs. Haven’t bothered to get another PCR. Just got on and isolated as 4 false positives meant I definitely had it and would’ve been irresponsible to go to work. I’ve continued to test positive on any subsequent LFs.

zaffa · 22/10/2021 18:52

@Yellowmellow2

You certainly have it. False positives are rare on LFTs so to have two positives, that’s fairly conclusive. Happened to me. Four positive LFs, symptoms, and two negative PCRs. Haven’t bothered to get another PCR. Just got on and isolated as 4 false positives meant I definitely had it and would’ve been irresponsible to go to work. I’ve continued to test positive on any subsequent LFs.
That's what I did. Ten days of isolating, I just couldn't take the risk of infection someone else. I had covid back in Jan and whilst my symptoms were much milder this time there were absolutely some cross overs - it was awful the first time and I wouldn't wish it on anyone. I'd be interested if hey ever find out why so many of us have tested positive on LFT and negative at PCR. I don't think it's just that one lab that has a problem.
disappointed101 · 22/10/2021 18:58

For those asking why positive on lateral flow negative pcr I wonder if it is due to specimen? When my son tested positive on lateral flow, the first was feint, did another which was darker and a third very dark. Maybe the more stuff you get out of your nose first, the better the sample there is? We did one after the other. Wonder whether snotty mucus inhibits things a bit?

BlibBlabBlob · 22/10/2021 19:02

@disappointed101

For those asking why positive on lateral flow negative pcr I wonder if it is due to specimen? When my son tested positive on lateral flow, the first was feint, did another which was darker and a third very dark. Maybe the more stuff you get out of your nose first, the better the sample there is? We did one after the other. Wonder whether snotty mucus inhibits things a bit?
Yes I think this is why on many tests you have to blow your nose first. Getting a bunch of snot on the swab can obscure the result.
disappointed101 · 22/10/2021 19:15

My son did blow his nose first as well though!

sociallydistained · 22/10/2021 19:22

Teenager I nanny for had this result yesterday. Positive PCR today just in time for half term. The rest of us biding our time. She has no symptoms as of yet.

dementedpixie · 22/10/2021 19:24

Unlikely to get a false positive on LFT tests as they are very specific. More likely to have a false negative PCR