There is no conspiracy, just some conspiracists with a very poor understanding of how the testing works, cherry picking isolated facts and twisting them painted in a technical veneer.
Discussing PCR cycle thresholds is a distraction and diversion, labs only proceed to calculate the viral load after a positive detection, primarily because the system is deliberately weighted towards false positives which is the safe option, but these are all filtered out when viral loads are calculated.
Firstly, the labs just do not have the time to test all the samples collected to a deep thermal cycle threshold. Most are processing using the system defaults of 20 to 30 thermal cycles(equipment dependant) requiring between 30min to 60min to complete a PCR run.
The typical systems use 20 to 30 thermal cycles, the reports comparing the BGI PCR system are discussing the ability of the BGI to replicate the sensitivity and accuracy of the existing systems as part of a validation against systems most of which are not BGI. But even so it does not mean the BGI PCR systems are run to a high number of cycles as asserted by some detractor claims.
I believe the default BGI PCR use 30 cycles, the validation claim is that at 30 cycles the BGI will miss cases with very low viral load, not report false positives at a much higher rate. One cause/outcome is not the inversion of the other, asserting that the BGI needs more cycles to achieve low level sensitivity leads to more false positives is a false equivalence, because they just don't use it that way!
Secondly, the process is false positive biased at about 3% of all positives are false positives, and that is at the calibrated run length for the default of 20 to 30 thermal cycles(equipment dependant), so too many more cycles and you get a false positive anyway which is clearly not the case give how many positives are reported as a percentage of all tests. Do enough cycles with any machine and you get a false positive, which is why positive results are always repeated.
Finally, verification typically occurs by other means/methods and can take several days to complete, this is when you get confirmations of both viral load and the variant. After verification, the false positive rate falls from 3% of all positives to about 1 in 10000 of all positives, hardly an earth shattering conspiracy! :o
Discussing PCR cycle thresholds is a distraction and diversion, labs only proceed to calculate the viral load after a positive detection, primarily because the system is deliberately weighted towards false positives which is the safe option, but these are all filtered out when viral loads are calculated.
Firstly, the labs just do not have the time to test all the samples collected to a deep thermal cycle threshold. Most are processing using the system defaults of 20 to 30 thermal cycles(equipment dependant) requiring between 30min to 60min to complete a PCR run.
The typical systems use 20 to 30 thermal cycles, the reports comparing the BGI PCR system are discussing the ability of the BGI to replicate the sensitivity and accuracy of the existing systems as part of a validation against systems most of which are not BGI. But even so it does not mean the BGI PCR systems are run to a high number of cycles as asserted by some detractor claims.
I believe the default BGI PCR use 30 cycles, the validation claim is that at 30 cycles the BGI will miss cases with very low viral load, not report false positives at a much higher rate. One cause/outcome is not the inversion of the other, asserting that the BGI needs more cycles to achieve low level sensitivity leads to more false positives is a false equivalence, because they just don't use it that way!
Secondly, the process is false positive biased at about 3% of all positives are false positives, and that is at the calibrated run length for the default of 20 to 30 thermal cycles(equipment dependant), so too many more cycles and you get a false positive anyway which is clearly not the case give how many positives are reported as a percentage of all tests. Do enough cycles with any machine and you get a false positive, which is why positive results are always repeated.
Finally, verification typically occurs by other means/methods and can take several days to complete, this is when you get confirmations of both viral load and the variant. After verification, the false positive rate falls from 3% of all positives to about 1 in 10000 of all positives, hardly an earth shattering conspiracy! :o
"Ruck, ruck, ruck, ruck ....... Ruck, ruck, ruck, ruck"
