Lateral flow tests...

[sopositivelynegative]

Checked my LFT at exactly 30 minutes and at first glance there isn't a line, but if I hold it up to the light, there's a very pale shadow at the positive bit. So pale and you have to squint.

(Is there supposed to be a shadow? Like, a sort of place marker for where it would turn purple if did change colour?)

My LFTs all look negative, but after 30 minutes, they do turn positive. I know results after 30 minutes are supposed to be void, but everyone I've spoken to has said that theirs are always negative and stay negative.

Anyone had similar/understand the science of how these tests work?

@Muchtoomuchtodo

Blimey. I’ve always assumed that a line on a positive test would be really obvious. I never squint to see if I can make a second line out! So if that was my test it would have been reported as a negative and I’d have carried on as normal.

I'm a bit nervous because I've had contact with a contact of someone with Covid... "My" contact has tested negative with a PCR, but "her" contact has tested positive with a PCR.

I don't have any symptoms, but neither did the person with confirmed Covid!

Given the relatively high false negative rate for LFTs, I don't think the negative second test trumps the positive first test.

Positive LFT = book a PCR surely? Then you will know for sure either way.

I had a faintly positive LFT yesterday morning, booked a PCR at a walk through for 40 mins later and had my (negative) result later that night. No hassle!

My husband leaves his lying round for days and they never have a hint of a line.

And wouldn't it be strange if covid behaved exactly in line with how we measure time?

It's obviously not certain either way, so you're best doing a PCR for reassurance.

We've done billions of these in our house, I never look at 30 mins just glance at some point in the future. I've not heard or read anywhere that a line appears after 30 mins and is void!

Go for a PCR test. That first one looks positive to me.
I've done loads of these tests and I've never had any sort of line or shadow show up at all, even after leaving it lying around for an hour or so.

Go for a PCR to be safe if that’s negative ur ok

That's positive,you need a PCR.

Book a PCR Op good luck x

I'm still not convinced (you've all reported different experiences with what happens to the test after 30 minutes!) but as there's no consensus and the first LFT did have the faintest of lines at 30 minutes, I've ordered a PCR test just in case.

So this is yesterday’s lft. No symptoms at all.
Did a PCR yesterday morning and the result is negative.
This morning, lat flow test is negative.

Hmmm
Feel absolutely fine!!
Still going to isolate because it is possible and doesn’t have a huge impact on anyone in the house.

What do you all think?

And op, how did your test work out?

My sons lft was negative after 30 mins , looked at it after an hour and very faint line . He did a second one and after 30 mins very faint , pcr confirmed positive. If I hadn’t have looked after an hour he could/would have possibly infected a lot of school friends and teachers ect . Def get a pcr x

@ThankyouForListening I see a faint line on yours!

Received my PCR today and have sent it off. Now, to wait for results... I'm hoping for a negative by the weekend. Fingers crossed!

Yes, there is a line.
Subsequent tests have been negative- the pcr taken on the same day, the lat flow taken yesterday and dh feels absolutely fine.

He’s still self isolating in the house- wearing a mask in the communal areas and staying in one room to work and sleep, and nobody else is going into that room.
We are trying to be super careful, but it’s hard to sustain for 10 days tbh

look at 30 minutes, no more, no less

Faint lines are still positives. My daughter had the faintest of faint lines that appeared after 30 mins. We took a PCR and she was positive. Please don't dismiss a faint line.

Sorry OP, I know you're not ignoring it, my 'please don't ignore a faint line' comment was a general one.

What about the faint line that has a negative pcr and then two more negative lat flow and the person is perfectly fine?!
I can’t really see any advice for that. The cases are sky rocketing in our area according to the Zoe app, so we are being as cautious as possible but it’s frustrating.
Tho it would be more stressful if it was all positive.

my daughter had a very faint, squint or you'll miss it line come up at 40 minutes. Positive pcr the next day.

Well, despite the faint LFT line, the PCR turned out to be negative!

Good news, but it's made me trust LFTs even less. I'm always going to self-isolate if there's any doubt, but I'm not sure how reliable these things actually are...

Absolutely not.

I’ve had more of a result with orange juice

@sopositivelynegative

Well, despite the faint LFT line, the PCR turned out to be negative!

Good news, but it's made me trust LFTs even less. I'm always going to self-isolate if there's any doubt, but I'm not sure how reliable these things actually are...

I trust your judgment less than the tests. It was never a positive, especially after 30 mins. Everyone who’s had positives it’s always happened straight away.

@Mummybasketball I had a faint positive before 30 minutes with the first LFT. It's just it turned into a more obvious positive after 30 minutes, which I thought was odd.

@Mummybasketball I'm sorry but this isn't always true. On Tuesday night I had a faint positive. I looked at 30 mins and it wasn't there. I went back an hour later and there was a faint line that only appeared later. Most would of missed it.
I booked a pcr for the morning.
I then returned home from the pcr and did another lateral and it was strongly positive literally 9 hours later. I have attached pictures for reference. PCR confirmed.

[quote snapple21]@Mummybasketball I'm sorry but this isn't always true. On Tuesday night I had a faint positive. I looked at 30 mins and it wasn't there. I went back an hour later and there was a faint line that only appeared later. Most would of missed it.
I booked a pcr for the morning.
I then returned home from the pcr and did another lateral and it was strongly positive literally 9 hours later. I have attached pictures for reference. PCR confirmed. [/quote]
Again, that isn’t a positive test.