New Flow Flex lateral flow tests v the old style ones?!

[CiderWithLizzie]

My DD in sixth form has tested twice today - she’s been diagnosed with tonsillitis by the doctor - but does she have covid too?! Top test is old style LFD and bottom is new style version. I’m assuming positive but have ordered PCR. Luckily DH and I are both treble jabbed (very fortunate).

We wondered that but we had done tests from the same box a couple of days earlier and it was negative and one the next day was negative too. But others seem to be having multiple positives, all very confusing.

Honestly, the south west lab thing has basically proved that the positive LF were accurate, and were not picking up another virus. Even when the lab is working properly, you are more likely to get a false negative pcr than a false positive LF.
I read a lot about this because I had positive LF for 9 days and negative PCRs before finally getting a positive PCR on a postal test.

@ciderwithlizzie the Wolverhampton lab were mostly processing tests from the SW. BANES, NS, Wilts, Bris, Cheltenham, Glos, Forest of Dean, some areas of Wales also.
No one has said if that lab is now back in action but frankly if you are in the South West and you're getting pos LF and negative PCR I'd be very suspicious and please just trust the LF and isolate.

We are SW and cases have absolutely skyrocketed, local schools had whole year groups off last week because people (understandably) trusted the govt advice that a negative PCR trumps a pos LF so hundreds of positive kids who'd been told to return to school infected hundreds more, as well as the staff.

It’s weird that the old style lateral flow was negative too though…?

My son tested positive on flow flex but confirmed on PCR as well.

Husband picked up a box at local pharmacy but is not a flowflex from what I can make out. We are SW. still negative. Symptoms variable sore throat, headache, exhaustion, tight chest st night. Today I just feel dizzy snd no energy day 5.

Oh and weird sneezing every now and again. And shakiness in legs

@Tinysnickers

Honestly, the south west lab thing has basically proved that the positive LF were accurate, and were not picking up another virus. Even when the lab is working properly, you are more likely to get a false negative pcr than a false positive LF. I read a lot about this because I had positive LF for 9 days and negative PCRs before finally getting a positive PCR on a postal test.

Yes this, I read a negative PCR shouldn't over ride a positive LFT.

I got a positive lft on the new tests, but then a negative pcr.

I was feeling unwell so think/assume that the lft picked up a different virus rather than covid.

Last week on Tuesday I had A very faint positive lateral on a flow flex - I had had a sore throat for a few days and mild cold but wasn't feeling fantastic hence testing a lot- I also around this time did x2 old stile lateral flows and two other flow flex - out of all 5 I only had one faint positive and subsequent pcr was negative . Tested again on flow flex two days later preparing for a darker line but was negative as was one I've just done now . I am triple jabbed. I have read an article about if exposed to a cold and covid at the same time the cold wins out so I do wonder if I had been exposed but fought it off or something??? My boss (nhs) said it's not that unusual to have a false positive on a lateral flow hence why she wanted me back at work after negative pcr
I would have retested with a pcr had I had another positive or started to feel worse though

I was feeling unwell so think/assume that the lft picked up a different virus rather than covid.
No it didn't
My boss (nhs) said it's not that unusual to have a false positive on a lateral flow hence why she wanted me back at work after negative pcr
It is very unusual (not unknown) to have a false positive. I think it's 99% accurate for positive, less so for negative.

@Cookerhood

I was feeling unwell so think/assume that the lft picked up a different virus rather than covid. No it didn't My boss (nhs) said it's not that unusual to have a false positive on a lateral flow hence why she wanted me back at work after negative pcr It is very unusual (not unknown) to have a false positive. I think it's 99% accurate for positive, less so for negative.

Ok so are you saying the pcr tests are inaccurate then?

PCT tests are more likely to produce a false negative than LF is to produce a false positive.
LF require the presence of covid proteins to show the second line. They are tested for cross reactivity to make sure they dont react to other common viruses, eg colds, flu etc. Assuming the test has been done properly (not a teen contaminating with cola) is highly unlikely that a positive LF is incorrect.

If you actually HAVE covid, you could get a false negative on a PCR because:

• the swab didn't happen to pick up enough viral material to be detected on the pcr

-something happened to the sample during transit, eg too hot, too cold -something went wrong at the lab (eg the 43,000 incorrect immenaa tests)

30% of people who are actually positive may get a false negative pcr according to this on the BMJ website.
www.bmj.com/content/372/bmj.n287/rr

The flowflex are supposed to be more sensitive than the old LF, that's exactly why the old ones are being replaced with the flowflex.

These tests make my head spin.

DC have a virus. Negative on the LFT.

DH and I all Negative too. Still unsure if it’s covid or not.

If there are symptoms, do a PCR. Guidance is clear.

If the chance of a negative PCR (when actually positive) is higher than a positive LFD (when actually negative), why are we doing confirmatory PCRs after positive lateral flows?

That’s the thing. School issued new guidance saying that a LFT trumps a PCR. So makes me wonder the point of taking one. We are in the SW where the lab has been issuing false results.

I’m in the south west too. Our school guidance is that PCR is still the one to follow. Hopefully the lab issue has been sorted now?

I got the test centre staff to do my pcr as well to ensure that a good sample was taken so this also gives me assurance the negative pcr was correct. I would like to think following errors at other labs that pcrs more checks and controls are in place now 🤞🤞🤞

@CiderWithLizzie

If the chance of a negative PCR (when actually positive) is higher than a positive LFD (when actually negative), why are we doing confirmatory PCRs after positive lateral flows?

To kick start the awful Test & Trace process! Not sure what happens if you get a positive LFT, register it online, but don't go and have a PCR though. Presumably harassment from T&T nonetheless.

I definitely have COVID. Typical Delta symptoms. Positive LFTs five days in a row now. Including one from an older (non FlowFlex) type, which I did only in the nose because I can't cope with throat swabbing but it still picked up the COVID. And the only people I've been anywhere near in the last couple of weeks are DH and DD, both of whom have just finished their own COVID isolations (they had positive PCRs). So yeah, definitely COVID.

I am not reporting the result online or going for a PCR because I don't want the hassle of Test & Trace calls. Am isolating for a full 10 days of course, taking the first positive test as Day Zero, because I am not a COVID-spreading dickhead.

BUT also I'm a bit worried that a PCR would come up negative, and that would put me in a very difficult position as technically I could go out and spread it! And from everything I've read recently, false negative PCRs are alarmingly common but false positive LFTs, unless deliberately messed with, are very rare.

FlowFlex are definitely more comfortable to take and easier get a good sample. Whether it's because of this, or whether it's because they are more sensitive, I am a big fan of them. A positive result should absolutely be taken as confirmed COVID.

I can’t get my head round all this, if there’s a line on a LFT, how can it not be correct? What is the line picking up if not the presence of the virus it’s been invented to detect?

It’s easy to say isolate with a positive LFT and negative PCR but when you boss says you have to be in work you have no grounds to refuse as it’s the PCR that triggers isolation.

We have found PCRs are positive after positive LFT but I am aware of many people who have tested negative after a positive LFT.

My extended family have had negative pcr tests 3x in a row. When the LFT says positive and they have clear covid symptoms and have been in contact with a positive case.

@Madwife123

It’s easy to say isolate with a positive LFT and negative PCR but when you boss says you have to be in work you have no grounds to refuse as it’s the PCR that triggers isolation.

We have found PCRs are positive after positive LFT but I am aware of many people who have tested negative after a positive LFT.

Yes this exactly