covid-19: Inaccurate Testing?

[MrTShirt]

An excerpt from an email from a neighborhood GP on covid-19:

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Inaccurate Testing?
Here's something the talking heads aren’t talking about. It’s about the unreliability of coronavirus testing.
Whether or not all of the scary things we are hearing about this particular virus are true depends on accurate testing. Inaccurate testing can lead to higher death rates ans unnecessary hospitalization. According to the expert virologists and the CDC, test results may be inconclusive for the following reasons:


    Simple technical errors, such as improper collection, handling or shipping.
    The various reagents used in the testing kits may be flawed, creating diagnostic inaccuracy.
    It’s possible that a patient who tested negative will later test positive because, the levels of the virus vary from day to day. And they may easily be bflow the level od detection on any given day. According to Dr. Charles Chiu, director of UC San Francisco’s Viral Diagnostics and Discovery Center, “Viral load goes up and down,” said. “That’s the natural course of the disease. You can test a patient and they’ll be positive one day and negative the next day.”
    Another possibility is that the test sample may miss the area where the virus is. That would lead to a false negative test. A false positive is when a test tells you have something that in fact you don’t.
    It’s also possible the test can’t detect some strains of the virus. RNA viruses like coronavirus have a lot of genetic variability. And the tests may miss a genetic variability that lack the genome the test is looking for.


Dr. John Swartzberg, a specialist in infectious disease and clinical professor emeritus at UC Berkeley’s School of Public Health, says it like it is, “We don’t have a test that can definitely say someone is not infected.” And, that’s not all.
Just the other day researchers posted the results of their study of coronavirus testing on the NIH (National Institutes of Health) web site. The title of the report was, “Potential false-positive rate among the 'asymptomatic infected individuals' in close contacts of COVID-19 patients.” Here’s what they found.
“When the infection rate of the close contacts and the sensitivity and specificity of reported results were taken as the point estimates, the positive predictive value of the active screening was only 19.67%, in contrast, the false-positive rate of positive results was 80.33%. In the close contacts of COVID-19 patients, nearly half or even more of the 'asymptomatic infected individuals' reported in the active nucleic acid test screening might be false positives.”
For myself, I’m not much interested in the test, no matter how accurate or inaccurate it might be. The question is not what kind of viral infection you have, it’s what are you doing about the infection. If you have the flu, don't hesitate to come in for treatment

REFS:
Coronavirus false test results: With the push to screen come questions of accuracy
By Lisa M. Krieger. PUBLISHED: March 19, 2020 at 3:11 p.m. | UPDATED: March 20, 2020 at 3:38 a.m. https://www.mercurynews.com/

Zhuang GH, Shen MW, et al. Potential false-positive rate among the 'asymptomatic infected individuals' in close contacts of COVID-19 patients. https://www.ncbi.nlm.nih.gov/


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Conclusion - a)  a lot to learn on the subject and b)  keep yourself as well as best as you can.