Originally published at: https://boingboing.net/2020/02/12/coronavirus-diagnostic-tests-d.html
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Looking around I can’t seem to find any info on WHY it is flawed. It’s a quantitative real-time reverse polymerase chain reaction (qRT-R-PCR) using standardized equipment and read-outs. This test works by selectively amplifying viral RNA segments to a much greater degree than non-viral RNA segments, so if you see a spike in the amount of copied viral RNA way above background from human RNA, you can confirm that there’s a virus in that person. The reverse PCR is needed because coronavirus doesn’t have DNA, it’s running on RNA. This kind of tech has been commonplace since 2005 or so and is well-validated, hence the feasibility of emergency authorization and distribution. The main risk I can envision for the test being flawed is primer specificity: if the primers aren’t completely specific for nCov-2019 RNA then you can get false positives or multiple peaks.
If anyone has more info on what’s wrong with the tests, please link.
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I do not (nor am I an epidemiologist, an MD, or what have you). The CDC is generally pretty reliable, though. Perhaps their website gives more insight on why they find the test problematic.
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Sorry, clicked in the wrong spot in replying to you. I checked the CDC website and it doesn’t seem to have details published yet.
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Maybe they will. This is a pretty fluid situation at the moment, so new information is emerging pretty quickly. If it’s true, that kind of sucks.
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The test instructions say that there are three markers, labelled N1, N2, N3, and that missing any of the three yields an “inconclusive” test. That suggests that “inconclusive” has been an observed outcome in the CDC lab.
I do hope this doesn’t indicate a significant mutation, and just teething pains for the kit.
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Never underestimate the power of placebo. - Now with added placebo!
Why, (cough) I’m feeling better already!
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Hopefully the results of all markers and no markers are conclusive.
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RNA tests are also very dependent on technique. Get even a tiny bit of ambient RNase in the sample or the kit and it screws everything up. A test that requires a match of three markers is even more finicky in response to even minor levels of contamination.
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Mention here that one of three assays not performing as expected:
https://twitter.com/ncovperspectiv1/status/1227639615147741184?s=21
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I see what you did there. 
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