Thirdly, as the PCR tests pick up dead virus fragments, the majority of so called 'cases' may be those who have dealt with the infection and may have become immune.
Except to quality for a pillar 2 test you require symptoms to book a test.
The chances of someone with covid symptoms having symptoms are far higher than someone without covid symptoms having it.
Someone shedding fragments post-infection is unlikely to have symptoms and therefore unlikely to have qualified for and booked a test.
There are exceptions - e.g. students. This was probably one of the reasons that my home city (Bristol) had a surge in 'cases' that quickly subsided.
Also, you can decide symptoms for yourself. If you think you are hot, you don't need to measure your temperature. Coughing and lack of taste occur with influenza.
Yes the symptom list is generally too vague but ultimately people with symptoms stand a lot more chance of having it than people without.
Ideally they'd narrow the list to dry, persistent cough, anosmia and thinks that seem common with covid and rarer for other viruses. But its still better than nothing.
Thats why global guidance including UK PHE/PHW and WHO say you need symptoms. Its a confirmatory test to a clinical diagnosis.
The shedding issues are going to be far bigger problems with people who arent sick or even possibly sick. Which again is why PCR is unsuitable for mass testing of asymptomatic people.
Its more useful under standard Pillar 2 with symptoms and this pillar makes up to 80% of our daily tests. So its not mass screening and requires symptoms to reduce the error rate.
The most simple explanation for the surge amongst students is that the students had covid which is what you'd expect then cases dropped away when it ran out of students to infect.
Just as happens every single year in uni halls.
Documents coming out thick and fast now.
NervTag have released more (useful) data:
Overall assessment of level and nature of risk, and level of confidence
PHE and NERVTAG consider this variant to require urgent investigation. It may be more transmissible than wild type virus, has multiple mutations, and the location of the mutations raises the possibility of antigenic change which could affect natural or vaccine derived
immunity. T
Its pretty useful that by chance the mutation knocks out one part of the 3 gene test lots of labs use. Allows us to track it rapidly without the need for sequencing.
Its a pretty good document, politically neutral, identifies possibly hazards and possible neutral non-hazards from the data.
Makes a change from hysterical, partisan texts.
Yes the symptom list is generally too vague but ultimately people with symptoms stand a lot more chance of having it than people without.
Ideally they'd narrow the list to dry, persistent cough, anosmia and thinks that seem common with covid and rarer for other viruses. But its still better than nothing.
Thats why global guidance including UK PHE/PHW and WHO say you need symptoms. Its a confirmatory test to a clinical diagnosis.
The big problem is that the non-specific symptoms of SARs CoV2 are common to pretty much all respiratory infections which at least 90% of the population gets one of more infections from every year. When doing the differential diagnostics decision tree the first mostly non-general non-specific symptoms for active SARs CoV 2 infections are no response to antibiotics/etc and a clouding on the lungs in chest X-rays. During the 2003 outbreak of SARs CoV 1 it was at the positive chest x-ray point in the diagnostics procedure that a RT/PCR test was done to ascertain whether it was actual SARs or one of the other half dozen common causes of viral pneumonia.
As for loss of smell / taste, thats also a non-specific symptom too. Common to other corona-virus infections as well as other viral infections. I've had it happen several times over the decades while suffering from heavy "colds". So its should be classified as a high frequency non-specific symptom rather than a specif symptom. A symptom that should be given greater weight during the differential diagnostic process. Thats all.
With the low prevalence of SARs CoV 2 and the higher prevalence of other infectious agents combined that can cause smell/taste loss a positive RT/PCR test result with smell/taste lost symptoms still has a high probability of being a Type 2 error. A false positive.
So given that the vast majority of the hundreds of thousands of RT/PCR tests done ever day are not the result of negative antibiotics response / positive chest x-ray clouding you can be mathematically certain that the vast majority of RT/PCR positive test results will be Type II errors. False positives.
To give one example. If the community outbreak of SARs CoV 1 in Amoy Gardens in Hong Kong in 2003 had been handing the same way as the current UK SARs CoV 2 testing procedures the "case" number in 2003 would have been 20,000 to 30,000 rather than the actual 321 clinically verified cases.
So given that the vast majority of the hundreds of thousands of RT/PCR tests done ever day are not the result of negative antibiotics response / positive chest x-ray clouding you can be mathematically certain that the vast majority of RT/PCR positive test results will be Type II errors. False positives.
I agree. That is why I have always estimated - in the only way I can - the level of false positives. I take the ONS daily positive cases divided by total PCR tests for a measured prevalence, and the ONS weekly survey estimated percentage of actual prevalence. Generally, the former is around 8-10 times the latter. As a rough estimate, this becomes a more reliable figure as the amount of mass testing increases.
It is an obvious, simple question to ask at any government presentation, or our for any one of us to ask our MP:
"If the ONS estimate a certain percentage prevalence in the general population, how come PCR tests are producing at least eight times as many positives on an increasingly representative number of daily tests?"
