No Rapid LFTs available?

Flugelhorn

Jeremy535897 said:

The other issue is specificity, because you also get false positives. Even at specificity of 95%, if 1 in 20 people have coronavirus, then whilst you pick up 72 cases out of 100 (number tested 2,000 as 1 in 20 have coronavirus), you also get 95 false positives (2,000 -100=1,900 x 5% = 95) (Bayes theorem).

absolutely specificity is equally important and while it has deleterious side effects (concern re having illness, cancellation of work / holidays / travel, anxiety for contacts) - the side effects are probably less than a false negative (if you are concerned about getting covid)

porkisnotmeat

Flugelhorn said:

Jeremy535897 said:

The other issue is specificity, because you also get false positives. Even at specificity of 95%, if 1 in 20 people have coronavirus, then whilst you pick up 72 cases out of 100 (number tested 2,000 as 1 in 20 have coronavirus), you also get 95 false positives (2,000 -100=1,900 x 5% = 95) (Bayes theorem).

absolutely specificity is equally important and while it has deleterious side effects (concern re having illness, cancellation of work / holidays / travel, anxiety for contacts) - the side effects are probably less than a false negative (if you are concerned about getting covid)

Which nobody is anymore.

silvercar

I read that specificity for omicron was around 98.5%.

MattMattMattUK

I did a test this morning as I was going to be driving a friend home from chemotherapy this afternoon, they had not asked me to, they were not worried, but I though I would play it safe. I have not met anyone else since Saturday morning when I had a coffee with my mum (quiet weekend doing DIY, then working from home), I have zero symptoms, I ran 10k on Sunday and 5k Tuesday and this morning, yet the test came back positive. I have done another and that was the same. My mum has tested and is negative, I have no idea where I could have picked it up from as I was at home on Thursday and Friday as well, no symptoms at all, heart rate, BP, SPo2 all bang on normal etc. 

I will however point out that if it was not for the very specific circumstances (being in close contact with a friend who was having chemo) I would not have been testing randomly. 

sheramber

The incubation period is 2-14 days.

jonnnyash

interesting thanks

Bobo_Brazil

silvercar said:

I read that specificity for omicron was around 98.5%.

Neither PCR nor LFT determine if you have infection or whether you are infectious. It simply measures genetic material (DNA swab). as Patrick Vallance has said this on camera several times.

"PCR and lateral flow tests do not distinguish live virus. No test of infection or infectiousness is currently available for routine use.." Britism Medical Journal
https://www.bmj.com/content/371/bmj.m4851

The test cannot give you "98.5% specificity" because it will not and cannot tell you whether you tested positive for Omicron, Delta, another Delta, South African variant, Kent variant, Brazilian variant, south London variant, or the other South African variant, or another forthcoming variant which the Government has spied on the horizon, and just signed hundreds of millions of £ worth of contracts for more lockdowns, tests, and quarantines - lasting another 2 years minimum. Starting later this year. according to published contracts on the Gov website.
Clever guy that Boris, he's spied this forthcoming variant months before it's got here.... shame about the hundreds of thousands (if not millions) of us who will not be able to simply shrug off paying for it in the form of further price rises, skyrocketing inflation, & simply won't be able to afford to live in our homes... 

silvercar

Bobo_Brazil said:

silvercar said:

I read that specificity for omicron was around 98.5%.

Neither PCR nor LFT determine if you have infection or whether you are infectious. It simply measures genetic material (DNA swab). as Patrick Vallance has said this on camera several times.

"PCR and lateral flow tests do not distinguish live virus. No test of infection or infectiousness is currently available for routine use.." Britism Medical Journal
https://www.bmj.com/content/371/bmj.m4851

The test cannot give you "98.5% specificity" because it will not and cannot tell you whether you tested positive for Omicron, Delta, another Delta, South African variant, Kent variant, Brazilian variant, south London variant, or the other South African variant, or another forthcoming variant which the Government has spied on the horizon, and just signed hundreds of millions of £ worth of contracts for more lockdowns, tests, and quarantines - lasting another 2 years minimum. Starting later this year. according to published contracts on the Gov website.
Clever guy that Boris, he's spied this forthcoming variant months before it's got here.... shame about the hundreds of thousands (if not millions) of us who will not be able to simply shrug off paying for it in the form of further price rises, skyrocketing inflation, & simply won't be able to afford to live in our homes... 

Given that omicron is virtually the only variant in the UK at the moment, it’s fairly safe to assume that anyone testing positive who hasn’t been out of the country in the last 2 weeks has omicron.
In any case, people are using the test to see if they have covid, they aren’t particularly interested in naming the variant. You may think it clever to say it can’t distinguish between live virus or not, the fact that people are testing positive after having tested negative is a fairly good sign that they have covid. It is an indicator that has helped people protect others from covid over the last year.