Lateral flow tests

I've posted this before so apologies for doing it again.

Regarding the accuracy of the LF tests.

Chance of a false positive : 1 in 1,000
Chance of a false negative: 1 in 4

So if it says you have COVID, you almost certainly have COVID. If is says you don't have COVID, you probably don't have COVID.

The point of doing them all the time is that they will catch a high proportion of positives who may be a- or pre-symptomatic.

That's why you should bother with them even if you're not showing symptoms.

We have not done them. To be honest, I have not seen anything that suggests everyone ought to be doing them.
We have had both vaccinations, and don’t go out much, especially not to crowded places or into anyone’s house yet. We live in an area with a very low number of cases.
I haven’t yet tried or wanted to try to visit my sister in a care home, but if I did, I guess I might have to do one.
I didnt realise they were meant for everyone. Are they?

I’m confused, does everyone need to do this? If so, where do you get them from?

I still have reservations about the accuracy of these tests, although the figures Alegrias has posted are reassuring. The problem for me is that my son in law who was working in the Covid Hub became infected with Covid and had clear symptoms. Obviously he stopped going to work and took one of these tests. The result was negative, and so he took another the following day and the result was negative. Only on the third day did the test say positive. He passed the infection to his wife and child. This destroyed my belief in theses tests which is why I don’t use them. I’ve had Covid (nothing to do with son in law) and have had the two vaccinations. I wear masks, socially distance, and use sanitiser. I’ve seen people in shops who walk past the sanitiser without a mask on. They annoy me. I’m not going to use these tests unless requested to by a dentist, doctor etc simply because I have little faith in them and because I’m vaccinated and have had the virus.

Incidentally these tests are probably useful for people who go to work every day, especially if not yet vaccinated or only partly vaccinated. I’m retired so not mixing with people in that way.

Likelihood of a false negative: 75%. 1 in 4. Likelihood of two false negatives one after the other: 56%? so nearly 50:50. Somebody better than me at stats will correct me if I'm wrong about two in a row.

If anyone thinks they have COVID, they need to get a PCR test.

No, that's wrong, posted too soon. Likelihood of a false negative is 25%. Still 1 in 4 though.

Wish I'd never started now

Yes I agree Alegrias, any symptoms do a test quickly. My son did two this week as he had symptoms but they both said negative. We think he’s just got a cold.

He little son had a cold last week.

When my son in law took the tests, he knew he had Covid because of his work and the symptoms and therefore he was already isolating.
Sadly to me, he and my daughter and their family have now left for New Zealand due to working under the extreme stress of working in the NHS through this crisis. Not the point of the thread I know, but very sad for us as we miss them so much. Two fewer doctors in the NHS now.

I take the tests twice a week. It is not a pleasant experience but if it prevents the spread of this awful virus a little discomfort is worth every second.

I do the twice weekly ones ,always test myself and always report the results.Mine have been negative always ,I work part time as a nurse so I am patient facing. I do feel those in the Government, NHS etc need to know that we are being attentive and doing our best to limit exposure. I’ve had both jabs and am hoping things can get back to normal ASAP.

I would do them as a precaution if I was still working.

maddyone

When my son in law took the tests, he knew he had Covid because of his work and the symptoms and therefore he was already isolating.
Sadly to me, he and my daughter and their family have now left for New Zealand due to working under the extreme stress of working in the NHS through this crisis. Not the point of the thread I know, but very sad for us as we miss them so much. Two fewer doctors in the NHS now.

I'm really sorry, that must be really difficult for you

Thank you very much JaneJudge.

GrannyRose15

The longer we continue testing, the longer restrictions will be in place.
It's time to get back to normal.

We can't go back to normal if the infection is still spreading. The people who most need to test are those without symptoms who may be asymptomatic. Of course testing will show up infections and will keep restrictions in place but the alternative of allowing infection to spread unchecked will be far worse. Those who have been vaccinated may feel invincible but even full vaccination doesn't guarantee full protection and there are many people still not vaccinated, especially the younger population.

I'm trying to be responsible. I test weekly on Ssturday as I now sing as part of a small worship team in church. I want to be sure I can't pass anything to them and they are testing too. It is the responsible thing to do!

Obviously everyone with symptoms need to get a pcr test done and isolate appropriately.

Cabbie21

We have not done them. To be honest, I have not seen anything that suggests everyone ought to be doing them.
We have had both vaccinations, and don’t go out much, especially not to crowded places or into anyone’s house yet. We live in an area with a very low number of cases.
I haven’t yet tried or wanted to try to visit my sister in a care home, but if I did, I guess I might have to do one.
I didnt realise they were meant for everyone. Are they?

Yes they are for everyone.
www.gov.uk/order-coronavirus-rapid-lateral-flow-tests
Order on the website above and they post a box of 7 tests to you. Even if you only take a test when you are planning to go out somewhere and have contact with people it will protect us all. I only do a test once a week , mainly because when I started I kept forgetting when I was due to do it so now I do one the same day each week. If I start going out more I may do twice a week.

I’ve just ordered my first pack of tests. I didn’t think I could have them as I live in Wales and I didn’t think they were being made available to the general public, but the request has gone through ok.

Alegrias1

No, that's wrong, posted too soon. Likelihood of a false negative is 25%. Still 1 in 4 though.

Wish I'd never started now

It's 1 in 16, if you take both tests at the same time.

If you take two tests separated by a few days, it's still 1 in 4 chance of a false negative for each test because you could have been infected in the intervening time.

The chances of a false positive result are minimal, so it's not true that surge testing is contributing to raised transmission rates.

I went out with a friend today for lunch outside. We both took a test (negative) before we went out. My friend gets regular PCR tests through work and I will take another LFT test in a few days. I fully expect the results to be negative because we wore masks when we were likely to be near anybody else and spent most of the day outside. However, it is to good to have the opportunity to fell a bit more secure, as we all go through this phase.

I've been doing them as additional precaution for seeing out grandchildren

Thanks growstuff. I was trying to get at the chances of having 2 negative LF tests if you are actually Covid positive. 1 in 16, thanks.

Alegrias1

Thanks growstuff. I was trying to get at the chances of having 2 negative LF tests if you are actually Covid positive. 1 in 16, thanks.

It will be 1 in 4 for each test on an individual sample, so two different samples will be 1 in 4 each. They're not connected mathematically.

I love a stats discussion in the morning

The chances for each one is 1 in 4 because they are independent events, but with the a priori assumption that you are Covid positive, what is the probability that 2 consecutive tests each return negative? 1/4 times 1/4, no?

Yes, I think that's right. If you take two tests while you are still at the same level of infectiousness (is that a word?). 1/4 x 1/4 = 1/16. It's probably higher than that because one of the reasons for a false negative is that the test isn't being done properly.