TotallyOz Posted August 6, 2020 Posted August 6, 2020 Testing is not what it should be. I wonder what this means for the rest of us? https://people.com/tv/alyssa-milano-tests-positive-for-covid-19-antibodies-after-negative-coronavirus-results/ Quote
Members Riobard Posted August 6, 2020 Members Posted August 6, 2020 The spectre of false negative, probability of 20% or greater error in this direction, depending on the day-to-day course of infection, is well known, even if by 2 virus tests Milano meant to convey she had each of the two versions. It is timing, integrity of sample, and imperfect assay. The only way to mitigate error is to test every day. Even then, no 100% accuracy. Getting in queue once for testing, without symptoms or without a suspected exposure event, at an arbitrary point in time over the past 6 months was essentially as beneficial as one dart toss. Not having symptoms and getting a negative test result while not presenting symptoms amount to the same thing. Possible false security. You may be infected at any time and should behave accordingly. Similarly, her timing of antibody screening would have been key. The article was poorly written and aimed at hype. That you can be sick and test negative does not underscore the reality of test error, as if it amplifies the problem. If you have signature symptoms you don’t really need test confirmation unless a more invasive Covid-19 specific treatment is warranted. The actual dilemma is that testing information related to error in results is poorly disseminated. [Attachments to follow] TotallyOz 1 Quote
Members Riobard Posted August 6, 2020 Members Posted August 6, 2020 https://globalnews.ca/news/7045805/coronavirus-test-false-negative-study/ JKane 1 Quote
Members Riobard Posted August 6, 2020 Members Posted August 6, 2020 (edited) Or here’s a brief summary on timing of test. Perhaps one concern among officials is that if you are transparent about testing flaws very few people will endure the hassle. Or you will just get more protests about one additional thing because the ruckus about CDC’s notoriously poor early test version will continue. After all, nobody has really found a viable testing solution since. As for Trump’s talking points, he should have been saying much testing yields false negatives rather than saying the only reason incidence rises is due to increased testing. But then the reality implied would be that true prevalence is even greater. That is poor optics for him. What an asshole. Not that I need any less restraint to put my fist through the TV screen when Fauci or Birx come on. Edited August 6, 2020 by Riobard Quote
Members Riobard Posted August 6, 2020 Members Posted August 6, 2020 (edited) I forgot to add to my rant that, in case you have not put it together, molecular or antigen versions of viral infection screening for entering aircraft or for essentially as ‘medical entry visas’ to destinations requesting this is a joke. Due to the high rates of false negative results, particularly for those infected but asymptomatic, presymptomatic, or paucisymptomatic (mild enough to be undetected via other screening methods such as body temperature). If you wish to be cautious in flying choices, I would suggest ignoring the false security of rigorous screening and that you focus on the prevalence rates where the airport exists driving the statistical likelihood of infected passengers, adjusting for variations in trip origin of those on board. Technically, the best way to ensure on-board clinical safety for all is a mandatory 2-week quarantine prior to embarking. That can never happen, certainly not for a return vacation flight. Edited August 6, 2020 by Riobard Quote
Members tassojunior Posted August 6, 2020 Members Posted August 6, 2020 The Brits seem to have solved the problem with a 90-minute test box smaller than a shoebox. Same guy who invented the DNA nutrition test box. The National Health Service is putting them in hospitals, airports, etc. quickly. A lot to be said for having a national health service. https://www.bloomberg.com/news/articles/2020-08-06/how-a-dna-test-machine-mutated-to-find-covid-in-90-minutes https://www.bbc.com/news/uk-53632043 Quote
Members Riobard Posted August 6, 2020 Members Posted August 6, 2020 (edited) A lot of places are doing rapid result SARS-CoV-2 tests. The problem of turnaround time was not identified in the Milano piece because the method of testing is often not the issue. These new tests such as Nudge in UK are no better in accuracy. They are better for expediency in results where a positive test flag would expedite control measures. However, the high rate of false negatives among test recipients is a problem if other screening measures are sidelined, such as evaluating conditions that elevated exposure risk in the previous few weeks. Again, for example, if prevalence ascertainment bias is 5-fold official reported incidence of 2% of population over one year year, and there is a 50% accuracy rate over the 7-day window of pretty much any test sensitivity whatsoever, the chances per test of hitting the right day for seropositivity is: .1 incidence/pointprevalence X .5 accuracy X .019 week/yr = .00096, or 1 in 1,041 ... how would that be for blood glucose threshold detection performance? More non-transparentjournalism. If the public knew vast amounts of money was being printed to fund such flimsy bandaid endeavours it might have a thing or two to say about it. It’s a blitz; do the isolation thing that is opposite of tube shelter but know the facts. Testing evolution is coming along but getting beyond mediocre remains a long ways off. Currently better to assume infection and to temper risk according to known prevalence. If mortality rate is 5% and transmission R is 1.0, you need 20,000 tests to potentially prevent one death by having isolated a seropositive. You get a lot more deaths through the flaw of false negatives being conflated with non-infection. I would prefer a ramping up costly life-saving equipment and resources. Wartime blitz bubbles, my bitches, blitz bubbles. Edited August 6, 2020 by Riobard Quote
Members tassojunior Posted August 6, 2020 Members Posted August 6, 2020 Germany has found dogs can easily be trained to sniff out Covid infections: https://www.bloomberg.com/news/articles/2020-07-24/dogs-can-sniff-out-coronavirus-infections-german-study-shows Quote
Members Riobard Posted August 6, 2020 Members Posted August 6, 2020 (edited) Welsh Cor-ona-gies, etc ... I like it. Better than a swine and a horseshoe bat crossing paths at the wrong time and place. And of course I don’t mean Peppa, Wilbur (or the Count). I mean the guy that needs to be vetted out. Set those sniffers on Hamburg, whatever it takes while getting to German Shepherd immunity. But since most infected droplets containing the pathogen drop down with gravity, I am curious about how canines differentiate among ground zero presence, shoe soles, and nasal-pharyngeal hosting. I’ll have to read more about it later. It is not the same as olfactory monitoring for malignancies or prohibited substances. Edited August 6, 2020 by Riobard TotallyOz and tassojunior 2 Quote
Members Riobard Posted August 7, 2020 Members Posted August 7, 2020 Sniffers not without problematic limitations ... https://slate.com/technology/2020/08/covid-19-sniffing-dogs.html tassojunior 1 Quote