LFTS are pretty much useless with Delta, aren't they?

[MareofBeasttown]

DS, 17, is positive. He had his first Pfizer jab last week, and then had mild body ache and fatigue, which we thought were due to the vax. Did two LFTS, was negative on both. Symptoms persisted and he got a sore throat, so we got a PCR. Positive! Isolating now but I guess we may all get it.

We should have done a PCR right away but we did confuse the symptoms with the vax side effects.

Yep. I was informed at the weekend that a colleague tested positive. I wasn't technically a close contact but I went and got a PCR and did a few lateral flows in the meantime. Every single lateral flow was negative. PCR was positive. I am asymptomatic so if I hadn't had a PCR I would have been carrying on as normal assuming the LFTs were correct.

Lfts have been known since the beginning of all this testing for throwing up more negatives than would be desirable. Not only Delta. It's why in many places/situations they aren't accepted.

It’s also good to know the skew, which is towards being accurate in the case of a negative for both.

Sid you want a cheap test, and the “cost” it missing a positive is low, then LFT is for you.

But if you want accuracy in terms of catching a positive, then it’s PCR. But they are more pricy.

Both PCR and LFT are good at showing negative when you actually don’t have it.

(This is where I looked: www.healthline.com/health/how-accurate-are-rapid-covid-tests#other-types-of-tests.)

We will be using LFTs when we travel home from Spain as the marginal benefit of knowing we have covid is massively outweighed by the huge inconvenience of having to stay put.

Sid? Say.

DD’s friend (23) did negative lateral flow test on Saturday but booked a pcr. That has come back positive.

How do you know it's Delta?

That's why if you have symptoms you use a PCR. LFTs were meant to be used in bulk on non-symptomatic people in the hope of picking up some asymptomatic cases to reduce the spread. They were never intended to pick up every case.

Peteycat aren’t almost all cases Delta now?

Im not sure my Ds1 tested positive on a, LFT at the beginning of the summer holidays, PCR confirmed d a couple of days later, we live in Bolton so im assuming it was the Delta varient?
Good news was though, Ds felt rough for a couple of days, and neither myself, Dh or Ds 2 tested positive c

LFT agave only ever picked up 65 to 75% of asymptotic cases. There is no research been carried out in the effectiveness of LTF specifically with the Delta variant.

@Waxonwaxoff0

Yep. I was informed at the weekend that a colleague tested positive. I wasn't technically a close contact but I went and got a PCR and did a few lateral flows in the meantime. Every single lateral flow was negative. PCR was positive. I am asymptomatic so if I hadn't had a PCR I would have been carrying on as normal assuming the LFTs were correct.

How are work with you staying home?

I think that the lateral flows also pick up cases when they are at their most infectious (but which otherwise be asymptomatic), so I think they can still be very useful.

Two families I know did lft last week and those who tested positive on lft then got positive pcr and those with negative lft tested negative on pcr too.

There’s some false negatives at work (I’m in a hospital) but all positives have gone on to get positive pcr results so it’s pretty good but not perfect.

They are totally useless. I'm positive (PCR tested with symptoms) and LFT have been negative, like stark white negative, the whole time.

The UK government bought 100s of millions of LFT from an obscure company, Disruptive Nanotechnology, via Cummings' 'Operation Moonshot' last year. They are made in China on behalf of a US company called Innova.

In June this year the US Food and Drug Agency (FDA) warned the US public to stop using the Innova test for detecting infection and suggested that any unused tests should be destroyed, binned, or returned.
There's a reason the government are handing them out like sweets to all and sundry, and it's not necessarily driven by science, as at the time Cummings’ said ‘We want to get ahead of the science’, it was a political decision, to be seen to be doing something, whether of any use or not.

@Pissinthepottyplease

LFT agave only ever picked up 65 to 75% of asymptotic cases. There is no research been carried out in the effectiveness of LTF specifically with the Delta variant.

This obviously Having said that I know of many many assymptomatic/ mild symptoms cases picked up by them so I can't complain It's just one of a range of tools to use?

DS had mild symptoms and tested positive with LTF and negative with a PCR test done later on the same day. Another PCR test a few days later came back positive.

Likely to be delta as we are in a delta hotspot.

I know several symptomatic people who got a positive lft before their positive pcr.
It might not pick up all, but any are better than none.

They were good on my household, all 4 of us had positive LFT and then went on to have positive PCR tests. My line was very faint and I had the mildest symptoms but the rest of my family had stronger, more obvious lines.

@sleepwouldbenice of course. I was trying to make the point that a few personal stories of LFT missing some cases later picked up by PCR tests does not mean the LFT are any less able to pick up asymptotic cases of the Delta variant.

We'll see, I've had 2 negative LFTs over the last few days when I started feeling a bit coldy but took a PCR today as started with a bit of a fever so wanted to be sure.

Will find out when the results come in!

Anecedata here Dd, Dh, Db and neighbour all had positve LFTs just at/ prior to onset of symptoms, I can only assume it's delta. Dd and DB's pcr is back (positive) DH, mine and Ds's are awaited (we have negative LFTs)

In June this year the US Food and Drug Agency (FDA) warned the US public to stop using the Innova test for detecting infection and suggested that any unused tests should be destroyed, binned, or returned
Well, that's unfortunate - the NHS staff are given the Innova ones in huge boxes.
We do them as a family and assume that if we are all negative that is a confirmation in itself. I wouldn't necessarily just do one test on one person and take it to be accurate. But the accuracy increases when several negatives are produced at the same time within one household.

The issue is that there is not the capacity in the UK for PCR testing to replace LFT. That is why the end of self-isolation today for the double-vaccinated does not come with a requirement for PCR tests (except NHS and social/care workers).
I wonder if the government have a plan for something to replace the LFTs that isn't as costly and time-consuming as PCR for non-symptomatic people. Or is this mass screening of non-symptomatic people going to end?
Other countries have saliva tests, will the Uk do this?

DD2 had a positive LFT with no symptoms before having a positive PCR. A few days later we had the same experience with DD1. I had negative LFT and PCR both times. This was a month ago in the NE so probably delta. They worked for us.