Lateral flow

[blahblahblah321]

Lateral flow - what is the point?!

So long story short (as short as I can make it!)

DS had friends around last night. Due to a couple of factors - inc one friend testing positive previous day ( non contact, but they had seen him earlier in week), group were cautious so all did an LFT before meeting - all fine.

Today one friend tested positive, meaning all friends now isolate obviously.

So all of these events that go ahead on the proviso that you have a neg LFT, what's the point? As you can test positive the next day and still have risked others.

I just don't get it, and feel flipping frustrated ( it has a big impact on us all with DS now isolating)

I don’t get the mumsnet obsession with LFT’S either. You see it on posts all the time.

LFTs aren’t that sensitive and only pick up when the viral load is quite high. They’re only supposed to be used as a way to possibly identify non symptomatic cases and not to ‘prove’ your negative as you could still actually be in the early stages.

Because they will pick up a large proportion of cases.

Pcrs give a fairly high false negative as well: www.bmj.com/content/369/bmj.m1808

You can conclude you are very likely to be positive from either positive result but you can't be absolutely sure you are negative from either.

This is the quandary ...

TBH PCRs are exactly the same. You can take a PCR today and it comes back negative. You can take one tomorrow and it comes back positive.

Tests can only tell you if you have the virus today.

I would be wondering why they took another test. Most I know only test if they ‘have’ to, for whatever reason.

The point is that 1/3 of people are asymptomatic.

So when you have a group about to meet, the LFT will remove 1/3 of the Covid cases. All those with symptoms will be removed, so you are left with just the group who have (unknowingly) been in contact with someone, but not yet showing symptoms/testing positive.

Yes, they are there in the group, so you haven't removed everyone, but you have reduced the people with Covid as far as you can.

I'm curious as to how the kid with the positive test managed to go from fine, to developing symptoms, to getting a test, to getting a result in 24 hours. Did he feel absolutely fine the night before or should he not have met up at that stage?

Morning @eurochick , he tested positive on an LFT with no symptoms. The group were trying to be sensible - they were going away this coming week and didn't want to risk meeting if one of them was ill so had agreed to test themselves before hand. It will be confirmed with a PCR too

@SpringRainbow

TBH PCRs are exactly the same. You can take a PCR today and it comes back negative. You can take one tomorrow and it comes back positive.

Tests can only tell you if you have the virus today.

I would be wondering why they took another test. Most I know only test if they ‘have’ to, for whatever reason.

@SpringRainbow , the group had agreed to take another test as other friends were in the mix on Saturday night. So they had been asked to test due to the friend who had already been tested positive earlier in the week and so the friends who had already tested negative Friday tested themselves again too.

It could have been a false negative, but there is also always a point at which someone will test positive for the first time. The test can't predict what happens tomorrow. You could say what's the point of pregnancy tests in the same way.

The point is some symptomless people test positive on them so they can then isolate. They are apparently quite accurate on delta variant if taken properly. Exhibit 1, LFT of my symptomless DC who was taking them twice weekly for high school. Without the LFT we would have had no idea they were Covid positive.

Your post doesn't really make sense as whatever test you take would be negative until the day it's positive

How could it be otherwise?

But he would have been positive the previous day @caughtinanet ?

@blahblahblah321

But he would have been positive the previous day *@caughtinanet* ?

How can you know that? There's no set incubation period and logically as it's a binary test there must be a minute when it changes from negative to positive.

@blahblahblah321 I agree with caughtinanet your post really dosen't make much sense.
It is like any other test. An example is a pregnancy test. You may well be in the early stages of pregnancy but if you test a day too early it will be negative. A test a day or two later will be positive.

LFT are not a fail safe. They are just helpful in weeding out some cases. If you take one when there is not enough virus present to detect then it will be negative. That does not mean that 24 hours later the situation will be the same.

When my daughters bubble burst at school, the first thing I did was lateral flow us all. Hers was positive. No symptoms.

We kept her a bit isolated (we were eating meals in the garden anyway, but moved my son down to the middle floor and stopped them sharing a bathroom)

I'd wear a ffp2 mask to take her lunch and breakfast, and she kept the window open at all times.

Without lateral flow, the person who burst the bubble wouldn't have known till later, probably infecting mor people.

My daughter wouldn't have known, probably infecting us in turn.

As it stands we stayed Covid negative and are off to Greece on Friday. Without LFT, that holiday would probably have ended up cancelled.