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Mystery in Wuhan: recovered coronavirus patients test negative then positive

npr.org

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Re: Mystery in Wuhan: recovered coronavirus patients test negative then positive

#51

Post by [deleted] »

frabbit wrote: post #7
dboreham wrote: post #4

Earlier quoted context omitted.

The article mentions RNA implying that this is the PCR test not an Antibody test. False positives exist with the PCR test. Information I could find suggests the primary cause is sample contamination. So running the test multiple times through different labs and clinicians is an obvious workaround.

Surely this is not a false-positive, but rather a false-negative? That is, the patients were observed clinically to have caught and recovered from the virus, yet the test shows no trace of the viral infection.

[deleted]

Re: Mystery in Wuhan: recovered coronavirus patients test negative then positive

#52

Post by smallnamespace »

lone_post wrote: post #47
gentleman11 wrote: post #23

> They all requested anonymity when speaking with NPR because those who have challenged the government's handling of the outbreak have been detained. We need to be more hesitant to praise their pandemic response

The Communist Party enjoys the luxury of dissent being a punishable offense. The media, the citizenry, the private sector are all held hostage by the absolute authority of the Party. I'm not sure why, but the media seems so eager to accept the official CCP narrative and take the lack of clear dissent from within China to mean China should be held up as a model Nation worthy of praise while simultaneously ignoring all…

> Please don't use Hacker News for political or ideological battle. That destroys the curiosity this site exists for.

> Eschew flamebait. Don't introduce flamewar topics unless you have something genuinely new to say. Avoid unrelated controversies and generic tangents.

Re: Mystery in Wuhan: recovered coronavirus patients test negative then positive

#53

Post by unwoundmouse »

lostlogin wrote: post #17
frabbit wrote: post #7

Earlier quoted context omitted.

Surely this is not a false-positive, but rather a false-negative? That is, the patients were observed clinically to have caught and recovered from the virus, yet the test shows no trace of the viral infection.

> Surely this is not a false-positive, but rather a false-negative? Both are possible and either mess it all up.

This is the correct answer

Re: Mystery in Wuhan: recovered coronavirus patients test negative then positive

#54

Post by wangii »

as far as I know, cases of 're-positive' have been reported in Chinese websphere for a while, and there had been doubts and official clarifications:

re-positive report: http://www.bjnews.com.cn/feature/2020/03/05/699575.html (2020/03/05)

expert stance: http://www.bjnews.com.cn/news/2020/03/12/702870.html (2020/03/12)

it's about lives and I don't think anyone believe in govt. lightly. so do you.

Re: Mystery in Wuhan: recovered coronavirus patients test negative then positive

#55

Post by dmoy »

lone_post wrote: post #47
gentleman11 wrote: post #23

> They all requested anonymity when speaking with NPR because those who have challenged the government's handling of the outbreak have been detained. We need to be more hesitant to praise their pandemic response

The Communist Party enjoys the luxury of dissent being a punishable offense. The media, the citizenry, the private sector are all held hostage by the absolute authority of the Party. I'm not sure why, but the media seems so eager to accept the official CCP narrative and take the lack of clear dissent from within China to mean China should be held up as a model Nation worthy of praise while simultaneously ignoring all…

There's CCP spread suggestions that coronavirus originated in the US (and was brought to China by the US army?). I don't think we're accepting all of CCP's narrative, because some of the ideas are quite obviously batshit crazy.

I don't many outside of China accepting everything the CCP is saying about coronavirus.

I do think it's probably worth waiting to evaluate until we have more real, verifiable numbers. Some of what people are saying is likely true. Some of it is likely not.

Re: Mystery in Wuhan: recovered coronavirus patients test negative then positive

#56

Post by hinkley »

gojomo wrote: post #37
hinkley wrote: post #28

Earlier quoted context omitted.

Hol' up. > blood 3/307 (1%) Why isn't their blood rotten with virus?

I suspect it's because this virus is optimized to enter cells that line the lungs/respiratory tract, then also sheds back that same way. Meanwhile, cells in, and along, the bloodstream aren't infected – and are most-trafficked by the body's immune response, including virus-destroying antibodies. (Why are rodents more prevalent in the walls/crawlspaces of a dwelling, rather than the hallways?)

But the lungs are full of blood, that's how we breath.

So it's spreading mucosally or through connective tissue?

Re: Mystery in Wuhan: recovered coronavirus patients test negative then positive

#57

Post by rurban »

This is entirely expected. Ex-positives develop antibodies, so that they are immune against further infections. Since the virus is so infectious it can easily lead to further infections, but the antibodies can contain it. Same happens with flu vaccination. The new PCR tests are so overly precise, that they can measure the new losing virus cells.

Big question is if the re-positives are infectious again. Doesn't seem to be plausible, but could be. It's a new virus with a different, stronger header.

Re: Mystery in Wuhan: recovered coronavirus patients test negative then positive

#58

Post by zerocrates »

hprotagonist wrote: post #22
im3w1l wrote: post #10

Earlier quoted context omitted.

The PCR can detect if there is virus in the swab. But the swab may not have scooped up any virus even though the person had some.

my longstanding argument against theranos, by the way (like, since 2005), was "look. if i go down to the beach with a bucket and take a bucket of water and put it in my super accurate shark detector van, it doesn't mean the beach is safe to swim at!"

To be fair at some level that's an argument against blood testing in general.

Re: Mystery in Wuhan: recovered coronavirus patients test negative then positive

#59

Post by usrusr »

hprotagonist wrote: post #9
baxtr wrote: post #8

Earlier quoted context omitted.

In general PCR tests are highly sensitive. Even smallest viral loads can be detected (Edit) added in general above due to valid points in the comments below

if: - you do them right - your reagents are good - the kit was assembled properly - there's no contamination in the machines - you got a good sample - ... The capability for a highly sensitive and accurate test in no way guarantees that a randomly sampled administration of that test is going to meet the high standard that the test may be capable of.

Even if you do everything perfectly a PCR test will still not be able to tell working virus copies from shattered remains.

Re: Mystery in Wuhan: recovered coronavirus patients test negative then positive

#60

Post by tehjoker »

AzzieElbab wrote: post #48
devy wrote: post #44

Earlier quoted context omitted.

Exactly! For any medical tests, there are 2 measurements: sensitivity and specificity, one to judge false positive and another judge the false negatives. https://en.wikipedia.org/wiki/Sensitivity_and_specificity

Spain sent testkits back to China because they were unreliable

In the NYT article on Italy today, frontline medics were saying that clinical symptoms were anecdotally more reliable than the tests because there are too many false negatives. Not sure whose tests they're using but I've heard similar things about US PCR tests.

https://www.nytimes.com/interactive/2020/03/27/world/europe/...

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