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Original poster

4 LFTs - 2 positive, 2 negative - chance of positive PCR?

59 replies

Awcw1234 · 17/12/2021 11:43

As above,

Tested 4 times since last night. Two came back negative but not straight away. How common are false positives on lateral flows?

I’ve been for a PCR this morning x

OP posts:
ratussbaguss · 17/12/2021 12:08

Unusual to get a false positive, you've probably got covid I'm afraid

Original poster
Awcw1234 · 17/12/2021 12:12

Even if the positive results took a while to show up? One was read after the 30 minute window, the other positive showed within 30 minutes but very faint!

OP posts:
Original poster
Awcw1234 · 17/12/2021 12:12

Plus I’ve done another which has come back negative! Confused!

OP posts:
ratussbaguss · 17/12/2021 12:13

LFT aren't that reliable. Just wait for the PCR result

neverdidnt · 17/12/2021 12:15

I think the false positive rate is around 0.05%, so there’s only a 1 in 2000 chance of getting a false positive. The false negative rate is much higher, about 1 in 3. I wouldn’t count the test read after 30 minutes, but the faint line that appeared within the 30 minutes does suggest you may have covid I’m afraid.

Cornettoninja · 17/12/2021 12:59

Step back from the LFT’s and wait for your PCR results.

It is what it is and you’ll drive yourself bonkers overanalysing.

Original poster
Awcw1234 · 17/12/2021 13:16

I’m just being impatient. Worrying about Christmas and I’ve had to take today off work x

OP posts:
Mindymomo · 17/12/2021 13:29

Just wait for PCR now you’ve been and got one, no point doing any more LFT.

Orchid876 · 17/12/2021 13:38

The timeline for me has been a very very faint positive LFT yesterday morning, which did not appear after the 15 mins you're supposed to check, it was more like 30 mins. PCR done yesterday afternoon came back positive this morning. LFT done this morning is a definite negative. I'm triple vaxxed and I have no symptoms, so the only way of confirming you're negative imo is a PCR. You can never presume a subsequent negative LFT is actually a negative, they aren't sensitive enough. I suspect, as in my case, because I'm triple vaxxed my viral load just isn't hight enough for consistent positive LFTs.

Original poster
Awcw1234 · 17/12/2021 13:48

Sorry to hear that Orchid.
These were my tests. Really hoping for a negative PCR 😬

4 LFTs - 2 positive, 2 negative - chance of positive PCR?
OP posts:
Orchid876 · 17/12/2021 13:51

Hmm yes, my first LFT looked like your second pic. Hopefully you don't have it, but best to wait for the PCR. I'm sure the vaccinations are doing their job and that's why I feel fine, so there's reason to be positive (no pun intended!).

Ahhhhhbisto · 17/12/2021 13:54

Our first positive lateral flows were even lighter than that Confused
Also if you done them close together its quite possible you didn't have enough virus on the swabs on the negative.

Crossing my fingers for you, but if i am honest. I think pcr will be positive. Sorry Sad

Original poster
Awcw1234 · 17/12/2021 13:56

@Ahhhhhbisto

Our first positive lateral flows were even lighter than that Confused Also if you done them close together its quite possible you didn't have enough virus on the swabs on the negative.

Crossing my fingers for you, but if i am honest. I think pcr will be positive. Sorry Sad

Oh, I took my lateral flows 2 hours before my PCR. Could I have compromised the PCR result?
OP posts:
Ahhhhhbisto · 17/12/2021 13:57

I don't think so. PCR's are so much more reliable than lateral flows. I really hope that pcr is nagative for you

AD80 · 17/12/2021 13:59

False positives are unusual, false negatives much more likely so I would be preparing for positive pcr 🤧

Ahhhhhbisto · 17/12/2021 14:00

This was my DS lateral flow on sunday. Pcr done monday, positive result tuesday.

4 LFTs - 2 positive, 2 negative - chance of positive PCR?
Original poster
Awcw1234 · 17/12/2021 14:00

I hope you are right. Afterall, I had to do the throat swab. Just don’t want to risk making anyone ill.

OP posts:
Ahhhhhbisto · 17/12/2021 14:02

How are you feeling in yourself? Hope you get a negative result.

Original poster
Awcw1234 · 17/12/2021 14:05

I’m worrying now that I might have wiped away any positive particles in my nose 🙈
I’m not feeling too bad. I’ve had a headache for 24hrs and I’m feeling tired. No typical covid symptoms!

OP posts:
Ahhhhhbisto · 17/12/2021 14:32

Please don't worry. It will be fine. Hope you stay well and you get your results quickly Thanks

Siuan · 17/12/2021 14:41

It's positive no matter how faint the line.

Original poster
Awcw1234 · 17/12/2021 15:11

I’ve also had two that are negative though. Wish these tests were as simple as pregnancy tests! 😂

OP posts:
WeRTheOnesWeHaveBeenWaitingFor · 17/12/2021 15:17

Seems like this is happening more and more. I know someone who keeps getting positive LTRs even though he has had a negative PCR.

ratussbaguss · 17/12/2021 15:19

@Awcw1234

I’m worrying now that I might have wiped away any positive particles in my nose 🙈 I’m not feeling too bad. I’ve had a headache for 24hrs and I’m feeling tired. No typical covid symptoms!
Bad headache and feeling tired are typical covid symptoms...
Orchid876 · 17/12/2021 15:33

They definitely are typical Covid symptoms, especially in vaccinated adults and children. The classic three are no longer typical and for the government to have not updated the symptom list is negligence. When most of my DDs class at school got Covid, for those that had symptoms, a headache was the common symptom in all of them.

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