Likelihood of false positive on LFT

[Ouchyhurt]

Had a very light line on LFT this morning, off for a PCR at 10 but what's the chances of a false positive. I had covid in February 2021 and suspected in March 2020. I'm double jabbed.

Ironically my LFT when I did have covid was negative

I had a positive lft on Monday which was really faint, have tested everyday since and now the positive is really strong, waiting for the proper test to confirm, but I feel rough 🤢

I had a +ve yesterday-I tested because DD has a temperature. I feel cold-y but DD and DH have returned two negative LFT tests each! Waiting for my PCR-my research says false positives are unlikely as LFT is less sensitive than PCR. False negatives much more likely

Bugger.

I had a false positive last week. It was a really faint line after 20 mins, you had to really squint to see it. I had done it because I felt a bit like I might be coming down with a cold. Got a PCR later the same day, along with my two DCs, all of which came back negative. Of course, there’s always the possibility that the PCR was a false negative but I never really developed any symptoms.

I've heard of a lot of false positives on LFTs

Worth getting another pcr to be sure of course but couple of months back, my son wasn't feeling great so I did a LF on him. He'd just had breakfast but not brushed teeth yet. It came back as strong positive. Turns out was likely the remains of the apple juice he'd just drink which can cause a positive result. Who knew! We went for a pcr and it was negative.
That was an emotional morning! Fingers crossed for you.

Thanks. No breakfast before testing so not that. Guess we'll see. If it's positive I give up!

Just done my main test so hopefully in the next 2 days I'll know if the lfts are right 🤦‍♀️

From what I've read the chances of a false positive are very very slim
The problems they have with LFTs are with false negatives

Yeah sadly I've read that too. I'm just clutching at straws!

Isolating is a pain but at least with a previous infection and vaccination you are unlikely to be ill.
What prompted the LFT, do you have symptoms?

@Sisisimone

Isolating is a pain but at least with a previous infection and vaccination you are unlikely to be ill. What prompted the LFT, do you have symptoms?

No, was meeting a friend for lunch so thought it considerate. Having said that my youngest has been slightly off colour this week with stomach pain but nothing else, I thought he was anxious about something but who knows. He also had it in February, we all did.

I'm not overly worried about having it, just annoyed if it's positive, it will mess up last few weeks of summer holidays for kids and my husband has important hospital appointments next week we'd have you reschedule

Have too, not have you

Do you have any symptoms? If you do then I would suggest it’s more likely to be a true positive.

However, DS (completely well) had a very faint line on lft on Sunday. Came back PCR negative, still no symptoms 4 days later. That said, I wasn’t able to read the result at 30 mins exactly and it could have changed after the time limit, but we tested by PCR to be safe.

Iirc at the height of the last wave it was 50/50 if a positive lft was a true positive or a false one. That was to do with the massive numbers of tests being taken.

I know a few people who have had several false LFT positives but subsequent PCR tests are negative.

Had you not long eaten or drunk anything before doing the test?

@Watsername

Do you have any symptoms? If you do then I would suggest it’s more likely to be a true positive.

However, DS (completely well) had a very faint line on lft on Sunday. Came back PCR negative, still no symptoms 4 days later. That said, I wasn’t able to read the result at 30 mins exactly and it could have changed after the time limit, but we tested by PCR to be safe.

Iirc at the height of the last wave it was 50/50 if a positive lft was a true positive or a false one. That was to do with the massive numbers of tests being taken.

No symptoms but now convinced I'm achy, I'm 100% sure this is in my head

(((Hugs))) DS’s results came back in 14 hours. You will know soon either way x

I waited 23hrs for my PCR-just got it back, positive. So odd though as DH (no symptoms) and DD (symptoms) both taken 3 negative LFTs apiece. They are now off to get PCRs

@Siameasy

I waited 23hrs for my PCR-just got it back, positive. So odd though as DH (no symptoms) and DD (symptoms) both taken 3 negative LFTs apiece. They are now off to get PCRs

Sorry to hear that. When I had it in February I wasn't too ill with it. I was exhausted but my DH was really really ill so I had a very stressful few weeks.

Thanks Ouchy hope your DH is okay now?
I feel ok, just had a sudden burst of energy and went outside to prune the Buddleia

You haven’t got any symptoms tho - DD has all the symptoms, more than I did, but still tested -ve three times.

My understanding is LFT is better for as-symptomatic testing?

Anecdotally all those I know that had a positive LFT went on to get a positive PCR result.

My sons SEN transport driver had a positive LFT followed by a negative PCR. Same happened with a student at my daughters school, so it does happen.

Negative PCR

@Ouchyhurt I had this - multiple faint positive LFTs, all within the time limit, three negative PCRs. The LFTs coincided with my symptoms and feeling as rough as a badger's arse. A few weeks later I took an antibody test as requested by the Zoe study - negative. So there is definitely at least one other bug out there with similar symptoms that causes LFTs to show positive, but isn't actually covid. I'm glad you got a negative result.