Med Cram had a segment on this, its believed to be false negatives. As some the current PCR test are highly inaccurate
Mystery in Wuhan: recovered coronavirus patients test negative then positive
21–30 of 123 posts
Re: Mystery in Wuhan: recovered coronavirus patients test negative then positive
#22Earlier 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
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!"
Re: Mystery in Wuhan: recovered coronavirus patients test negative then positive
#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
Re: Mystery in Wuhan: recovered coronavirus patients test negative then positive
#24Czechia got some quick tests from China. Their reliability was about 60% compared to lab, false positives and false negatives. I think DNA and RNA research is severely lacking in most countries. In a few years we will look at this year as 1960ies of computer engineering. Edit: source https://www.irozhlas.cz/zpravy-domov/ostrava-rychlotesty-kor...
Initially skeptical on your first claim but did find a source: https://www.businessinsider.com/coronavirus-spain-says-rapid... ( https://outline.com/uBBJvY )
Re: Mystery in Wuhan: recovered coronavirus patients test negative then positive
#25But they were not found to shed viruses.
Doesn't mean they were found not to.
Re: Mystery in Wuhan: recovered coronavirus patients test negative then positive
#26Earlier 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.
Or with a well-known phrase: garbage in, garbage out.
Re: Mystery in Wuhan: recovered coronavirus patients test negative then positive
#27Couple of thoughts: - I think we need to know a LOT more about the sensitivity, specificity, and accuracy of every test that's being deployed right now. I am 100% willing to believe that "testing negative and then positive" means "you have a pretty low viral load and our tests suck more than we're willing to admit out loud right now". - I think we need to be very clear that there are two kinds of tests: "you have an…
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Re: Mystery in Wuhan: recovered coronavirus patients test negative then positive
#28Earlier quoted context omitted.
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.
And if you swabbed an infected part of the body in the first place! In 205 patients with proven COVID-19 [...] bronchoalveolar lavage fluid was positive in 14/15 (93%), sputum 75/104 (72%), nasal swabs 5/8 (63%), brush biopsy 6/13 (46%), pharyngeal swabs 126/398 (32%), feces 44/153 (29%), blood 3/307 (1%), and urine 0/72 (0%). https://www.jwatch.org/na51116/2020/03/17/pharyngeal-and-nas...
Hol' up.
> blood 3/307 (1%)
Why isn't their blood rotten with virus?
Re: Mystery in Wuhan: recovered coronavirus patients test negative then positive
#29Earlier 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!"
Unless you dilute the water until it becomes homeopathic anti-shark water.
Re: Mystery in Wuhan: recovered coronavirus patients test negative then positive
#30Couple of thoughts: - I think we need to know a LOT more about the sensitivity, specificity, and accuracy of every test that's being deployed right now. I am 100% willing to believe that "testing negative and then positive" means "you have a pretty low viral load and our tests suck more than we're willing to admit out loud right now". - I think we need to be very clear that there are two kinds of tests: "you have an…
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
Even a 99.9% sensitivity will miss a few times when you're testing millions of people.