Good thread from @jneill on the importance of recording the number of tests actually concluded under each pillar AND recording the number of negatives (prevalence).
Therefore result as ALSO should be subdivided according to work, age, sex, ethnicity, care home resident etc.
Therefore result as ALSO should be subdivided according to work, age, sex, ethnicity, care home resident etc.
I also want to flag up issues about the gold standard test method RT-PCR.
There are a number of reasons why false negatives might be produced (no test is 100%) quite apart from the technology itself developing. This is a new virus. There will be fine tuning.
There are a number of reasons why false negatives might be produced (no test is 100%) quite apart from the technology itself developing. This is a new virus. There will be fine tuning.
1) variation in detection rate from different manufacturers. So which method/ kit being used. Need a subset to reflect this;
2/ Timing - low patient viral load; Might need more than one test.
or 3/. improper clinical sampling. How is this being Quality assured?
2/ Timing - low patient viral load; Might need more than one test.
or 3/. improper clinical sampling. How is this being Quality assured?
How do the Randox home test kits perform v professionally taken samples?
How are these being reported? It is inconceivable that PHE does not have reporting lines in their data sets for this.
How are these being reported? It is inconceivable that PHE does not have reporting lines in their data sets for this.
4/. Is the Gov trying some of the new saliva test kits? Likely better for home use? Or in settings where high quality nasopharyngeal swabbing is challenging (eg in care homes with people with comprehension difficulties or gag issues. Minimise aerosol production and infection?
We already know from reports in China, France, USA, S Korea that there can be several reasons for false positives.
And the range of performance is quite considerable. From 3% false negatives to 56% in some very overwhelmed Brooklyn clinics.
And the range of performance is quite considerable. From 3% false negatives to 56% in some very overwhelmed Brooklyn clinics.
Different companies test kits may perform differently too and the USA have been rushing through and short cutting some of the federal state approval processes.
There have also been some issues with suppliers of reagent materials delivering sub standard products.
And in 3 US CDC labs in the early days failed to follow their own SOPS resulting in contamination of samples.
And in 3 US CDC labs in the early days failed to follow their own SOPS resulting in contamination of samples.
I know this is difficult but it is also a normal part of getting to grips with a novel disease.
But that is why transparent reporting, including of negatives (and according to sub groups) and constant QA is critical
But that is why transparent reporting, including of negatives (and according to sub groups) and constant QA is critical
