RE: Test Design5 Jun 2020 20:41
Hi Ghia.
"The PCR test looks for 3 distinct signals in each sample (i) a positive or negative COVID19 signal based off E and N genes, (ii) an internal control signal to tell you that the PCR reaction has worked and (iii) an human “RNaseP” signal that tells you there is human DNA in the sample. Ideally, you get all 3 amplifying in a positive case. If you get no COVID signal and also get no RNaseP signal, good chance it’s not the best sample, or no sample at all."
If you don't have one of the following:
i) a positive or negative COVID19 signal based off E and N genes,
ii) an internal control signal to tell you that the PCR reaction has worked
iii) an human “RNaseP” signal that tells you there is human DNA in the sample.
...then I would assume the sample cannot be further tested, because the lack of any one of these signals is a show stopper.
I notice that i) includes the use of more than one gene, - we know the Primerdesign test uses just one gene, and we don't know if using one more gene is an easy task.
The Primerdesign assay is one if the fastest PCR tests available, so to detect and use more signals may increase processing time.
The company must be aware of the incorrect swabbing issue, as it will have had numerous discussions on the issue.
I trust the company to assure that if it is possible to modify a test to indicate when human error has occured during swabbing, then they would take steps to rectify is possible.