How reliable are pcr tests?

[rainbow]

I'm stressing massively as my granddaughter started with a cough and temperature almost 2 weeks ago, my daughter took her for a pcr test on day 4 which came back negative. My daughter also did a lft on herself which was also negative. For the last week my daughter has been coughing a lot and feeling unwell, she has been double vaccinated. I have spent time with them both over the last week as I felt mildly reassured by my grand daughter's negative test.

Now I'm starting to panic incase the test was wrong as I know there are false negatives. I thought about doing a lft but that probably wouldn't reassure me. I have had both az vaccines but I have read a lot about people testing positive after having both and still becoming very I'll or dying. I don't think I will ever be able to live a normal life again or be comfortable around d my grandchildren.

[Pamplemousse]

The PCR test is the supposed "gold standard", as it's used to confirm a positive lateral flow test and is also the only one that international bodies will accept.

If both the PCR and LF tests were negative, the chances of both being false are miniscule.

I jump every time I hear someone cough near me, so you're not alone in your anxiety on this matter.

[Lencoboy]

I don't intend to come across as dismissive nor as a Covid denier, but please remember that all other 'traditional' causes of coughs and common colds still haven't disappeared of the face of the earth ever since Covid first became a thing.

'Seasonal' factors such as high pollen counts and hayfever still remain as abundant as ever, which could very easily be mistook for Covid (and vice versa, of course).

[rainbow]

Thanks for the replies. I am worrying even more now as my throat feels strange, like there's lots of phlegm in it and a little bit sore. I do have hay fever which has been pretty bad and I also have been using the air conditioning in my car a lot too which I have read can irritate the throat. Other than that no symptoms but the anxiety is huge.

[Pamplemousse]

You've answered your own question there as to why your throat feels odd. In my case, swap post-nasal drip for hay fever and I have the same.

[elizabethalice]

My boyfriend and I both had a cold the other week. We both felt exhausted and achy, and I had a sore throat and slight cough. We had covid in January and have both had our first jabs, but I still freaked out worrying about it! We did a PCR each and 5 LF tests between us in the end and all came back negative. Fine now! People do seem to be getting colds again so if the tests are all negative I'm sure its that. If you're really worried and are coughing get a PCR, but then once you get your negative result leave it to rest.

[dorabella]

I don't intend to come across as dismissive nor as a Covid denier, but please remember that all other 'traditional' causes of coughs and common colds still haven't disappeared of the face of the earth ever since Covid first became a thing.

'Seasonal' factors such as high pollen counts and hayfever still remain as abundant as ever, which could very easily be mistook for Covid (and vice versa, of course).

Quite right Lenco - all the seasonal irritations such as summer colds, hayfever (which I suffer from) are still going round. People are so freaked out though by the obsession with Covid symptoms that they think everything is Covid. All respiratory viruses or allergic syndromes though so to be expected.

Testing - whether PCR or LF - seems to be little indicator of anything. Lot of debate over PCR - which is set at so a high a cycle that it picks up fragments of anything from boys to rent - can barely distinguish between Covid or a related respiratory virus ... as some scientists have argued. This obsession with testing needs to stop - in Scotland apparently they are going back to testing only on the hospital admissions rather than the public at large - UK should adopt general policy on these lines.

Interesting comments from Patrick Valance on the easing of restrictions and forward policies today.

[Gary A]

Testing - whether PCR or LF - seems to be little indicator of anything. Lot of debate over PCR - which is set at so a high a cycle that it picks up fragments of anything from boys to rent - can barely distinguish between Covid or a related respiratory virus

Lateral flow testing is around 60% accurate but is pretty valuable in finding possible infections and referring on to PCR.

PCR testing is very sensitive and the stories of it picking up “fragments of anything” are unsubstantiated nonsense. Yes, it’s possible for ANY test to show either a false positive or negative but the idea that the PCR test tells you nothing is pure waffle.

At the moment, the “obsession” with testing is used as a means to document the viruses spread. It aids in learning how the virus operates. It’s also about the only way we’ve had to try to prevent further outbreaks, given that around 1/3 of cases are completely asymptomatic but still shedding virus.

Testing should only be lessened when the evidence of the viruses reduced impact on public health is solid. Ironically, the only way to gather that evidence is to test more and measure up positive cases against severe illness. We’re beginning to see some shoots of that right now, but it’s going to take a good few months before we can definitively say that the vaccination drive has broken the link between infection and severe illness. Reducing testing now would leave us with the potential for vaccine efficacy results to be violently skewed.

[Lencoboy]

Lateral flow testing is around 60% accurate but is pretty valuable in finding possible infections and referring on to PCR.

PCR testing is very sensitive and the stories of it picking up “fragments of anything” are unsubstantiated nonsense. Yes, it’s possible for ANY test to show either a false positive or negative but the idea that the PCR test tells you nothing is pure waffle.

At the moment, the “obsession” with testing is used as a means to document the viruses spread. It aids in learning how the virus operates. It’s also about the only way we’ve had to try to prevent further outbreaks, given that around 1/3 of cases are completely asymptomatic but still shedding virus.

Testing should only be lessened when the evidence of the viruses reduced impact on public health is solid. Ironically, the only way to gather that evidence is to test more and measure up positive cases against severe illness. We’re beginning to see some shoots of that right now, but it’s going to take a good few months before we can definitively say that the vaccination drive has broken the link between infection and severe illness. Reducing testing now would leave us with the potential for vaccine efficacy results to be violently skewed.

You're right Gary. Ditching all Covid testing (unless already seriously ill in hospital with it, as was the case early on in the pandemic) is essentially sweeping the issue under the carpet, as opposed to increasingly hysterical over it.

Plus (dare I say it), I actually believe the polar opposite to Dorabella, in the sense that a large proportion of the population seem to be becoming more blasé about the Covid situation in the UK of late.

In fact, my current views on the matter are probably split 'middle ground' between those of say, Dorabella and Pamplemousse, plus probably more in line with both yours and Terry's.

[rainbow]

Lateral flow testing is around 60% accurate but is pretty valuable in finding possible infections and referring on to PCR.

PCR testing is very sensitive and the stories of it picking up “fragments of anything” are unsubstantiated nonsense. Yes, it’s possible for ANY test to show either a false positive or negative but the idea that the PCR test tells you nothing is pure waffle.

At the moment, the “obsession” with testing is used as a means to document the viruses spread. It aids in learning how the virus operates. It’s also about the only way we’ve had to try to prevent further outbreaks, given that around 1/3 of cases are completely asymptomatic but still shedding virus.

Testing should only be lessened when the evidence of the viruses reduced impact on public health is solid. Ironically, the only way to gather that evidence is to test more and measure up positive cases against severe illness. We’re beginning to see some shoots of that right now, but it’s going to take a good few months before we can definitively say that the vaccination drive has broken the link between infection and severe illness. Reducing testing now would leave us with the potential for vaccine efficacy results to be violently skewed.

So are you saying that you think the vaccines aren't reducing the amount of people who are becoming seriously I'll with covid. If so that really scares me.