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Does anyone know if there is testing error for CV19?


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Every test has false negatives and false positives. I read the same article that said it appears that the overall average for the US tests has about an 85% sensitivity (meaning about 15% false negatives). It’s hard to know better know because there are a variety of tests being used, and some may be less accurate than others. It also seems to be highly dependent on procedure of the test. The sample has to be taken fairly far back in the nasopharyngeal passage. So if a patient moves back while testing, or the tester doesn’t really swab far enough back...much more likely to be an inaccurate test. The specificity (amount of false positives) isn’t known at this point but seems to be lower. 

What we are being told is that a positive test is very useful, especially if it correlates with clinical history and symptoms. A negative test is less useful, especially if someone has a history or symptoms that would suggest having Covid-19. So if someone has a history of exposure and symptoms or symptoms that are very suggestive of covid-19, with a negative test....they should still act like they are positive as far as self-isolating. 

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4 minutes ago, Alice said:

Every test has false negatives and false positives. I read the same article that said it appears that the overall average for the US tests has about an 85% sensitivity (meaning about 15% false negatives). It’s hard to know better know because there are a variety of tests being used, and some may be less accurate than others. It also seems to be highly dependent on procedure of the test. The sample has to be taken fairly far back in the nasopharyngeal passage. So if a patient moves back while testing, or the tester doesn’t really swab far enough back...much more likely to be an inaccurate test. The specificity (amount of false positives) isn’t known at this point but seems to be lower. 

What we are being told is that a positive test is very useful, especially if it correlates with clinical history and symptoms. A negative test is less useful, especially if someone has a history or symptoms that would suggest having Covid-19. So if someone has a history of exposure and symptoms or symptoms that are very suggestive of covid-19, with a negative test....they should still act like they are positive as far as self-isolating. 

My nephew was given the opposite advice and I was pretty sure it was wrong.  He did keep self isolating anyway.

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25 minutes ago, Ausmumof3 said:

My nephew was given the opposite advice and I was pretty sure it was wrong.  He did keep self isolating anyway.

 

And they may have been wrong but I will also say give all health care providers grace. We are literally getting dozens of updates daily (I get them from our state Dept of Health, our county Dept of Health, three local hospital systems and my own practice). Information is rapidly changing and we are all learning. It’s a NOVEL virus for all of us. Individual doctors are trying their best to give correct information. But it’s really hard. 

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30 minutes ago, Alice said:

 

And they may have been wrong but I will also say give all health care providers grace. We are literally getting dozens of updates daily (I get them from our state Dept of Health, our county Dept of Health, three local hospital systems and my own practice). Information is rapidly changing and we are all learning. It’s a NOVEL virus for all of us. Individual doctors are trying their best to give correct information. But it’s really hard. 

Yes.  Definitely.  And thoughts with you all through the months ahead.  FWIW he didn’t see a GP they sent him straight to the testing clinic so I’m assuming the advice he was given was the same as they were giving to everyone at that point. I don’t think individual doctors etc are seeing Covid patients they all go through designated testing clinics.

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2 hours ago, Alice said:

Every test has false negatives and false positives. I read the same article that said it appears that the overall average for the US tests has about an 85% sensitivity (meaning about 15% false negatives). It’s hard to know better know because there are a variety of tests being used, and some may be less accurate than others. It also seems to be highly dependent on procedure of the test. The sample has to be taken fairly far back in the nasopharyngeal passage. So if a patient moves back while testing, or the tester doesn’t really swab far enough back...much more likely to be an inaccurate test. The specificity (amount of false positives) isn’t known at this point but seems to be lower. 

What we are being told is that a positive test is very useful, especially if it correlates with clinical history and symptoms. A negative test is less useful, especially if someone has a history or symptoms that would suggest having Covid-19. So if someone has a history of exposure and symptoms or symptoms that are very suggestive of covid-19, with a negative test....they should still act like they are positive as far as self-isolating. 

Thank you, thank you! This is exactly the information I was looking for. 

Thank you so much for being on the front lines of this crisis. My gratitude to health care professionals and scientists at this time is boundless. 

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I just listened to an interview with David Sinclair and he said of the two main types of tests being used in the US:

The PCR test (polymerase chain reaction) is 99.99% accurate.

The blood antibody test is accurate for positives but only 90% accurate for negatives.

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