Over half of Covid hospitalisations tested positive after admission • Hacker News Board

Re: Over half of Covid hospitalisations tested positive after admission

#41

Post by timr » Tue, Jul 27, 2021, 3:10 PM UTC

mizzack wrote: post #39

timr wrote: post #34

Earlier quoted context omitted.

> I have looked and I cannot even find how increasing CT values affect the false positive rate for the PCR testing. If my understanding is correct a single increment of CT essentially doubles the sensitivity of the test, so difference between CT value of 35 and 40 is 32 fold. I have never used this particular set of primers, but have done a lot of PCR. In general, at 30+ cycles, PCR is prone to spurious amplification…

> I strongly suspect that the goal was to cast a wide net (i.e. bias toward false positives) at the expense of accuracy, but then "cases" became some kind of top-line media metric... Then in January the WHO updated the diagnostic protocol [1] because of that false positive/low confidence problem. Unsurprisingly, case counts plummeted in the following weeks. [1] https://www.who.int/news/item/20-01-2021-who-information…

Yep. It was stunning to me that this was rarely mentioned in the press.

Re: Over half of Covid hospitalisations tested positive after admission

#42

Post by sokoloff » Tue, Jul 27, 2021, 3:12 PM UTC

bananapub wrote: post #13

sokoloff wrote: post #6

Earlier quoted context omitted.

The main point of the article (at least as I understood it) is that I could be hospitalized for an open fracture in my leg, tested for COVID while there, test comes back positive (either true or false positive) and be counted as a "hospitalized COVID case".

what suggests to you that there is any notable number of false positives?

Primarily that "all lab tests have errors" and if you test everyone who is hospitalized for any reason (which is sensible), you're inevitably going to get some false positives.

Secondarily, in any low-incidence scenario (such as might be the case for "COVID infections among the vaccinated"), even high specificity tests have a high false rate among positive tests.

Re: Over half of Covid hospitalisations tested positive after admission

#43

Post by killjoywashere » Tue, Jul 27, 2021, 3:12 PM UTC

dataflow wrote: post #28

forcry wrote: post #20

The most baffling thing is not standardising CT values for RT-PCR tests. I have looked and I cannot even find how increasing CT values affect the false positive rate for the PCR testing. If my understanding is correct a single increment of CT essentially doubles the sensitivity of the test, so difference between CT value of 35 and 40 is 32 fold. CDC is suggesting CT value of 28 for detecting breakthrough infections a…

Apparently it's even worse: "Different machines can produce different Ct values for the same sample, and the same machine can give different Ct values for different samples from the same person." [1] I'm not sure I even understand the statement, but I guess it means it could be that they (somehow) couldn't report them even if they wanted to. [1] https://medical.mit.edu/covid-19-updates/2020/11/pcr-test-re...

I ran one of the first labs to validate the original CDC assay (we got the controls to work). Ct numbers were a slippery slope we should never have gone down for COVID-19 PCR tests because snot is not like blood, a homogenous substance with well known homeostatic parameters that are under tight physiologic control. Do you know someone went swimming? Do you know if they were crying? Did they just eat some particularly spicy tacos? Do you know if they have Sjogren's disease? What's the humidity? Are they dieting? Add in the presence of long COVID, and just long post infectious shedding, and it's mildly amazing we can get this to work at all. Yes, the test platform produces the data and no, it should not be reported. The only thing we can really do is confirm presence of the virus.

Re: Over half of Covid hospitalisations tested positive after admission

#44

Post by [deleted] » Tue, Jul 27, 2021, 3:22 PM UTC

timr wrote: post #37

doesnotexist wrote: post #18

Misleading article since as they state "44 per cent involved people who tested positive in the 14 days before hospital entry. A further 43 per cent were made within two days of admission". Thats 87% are positive within 2 days of start of admission but the article is very blustery about the non-common case that people test positive after discharge for some non-covid admission reason.

They say this in the article, so I'm not sure how it's "misleading". The point (which the article discusses) is that it's fairly unlikely that someone being admitted for severe Covid has not already had at least one positive test prior to admission.

[deleted]

Re: Over half of Covid hospitalisations tested positive after admission

#45

Post by snegu » Tue, Jul 27, 2021, 3:23 PM UTC

raziel2p wrote: post #14

peteradio wrote: post #8

Comments so far seem to misunderstand the issue. People are not catching Covid in the hospital. They are in the hospital for non-covid reasons (broken leg, pink eye etc) but if they test positive it will show up in statistics as a "Covid Hospitalization". That is terribly misleading because we want to understand if Covid is causing an increase in hospitalizations, this is attributing other causes to Covid.

I mean, they may be catching covid in hospitals, there's no way to know for sure, but it seems unlikely to account for all these cases. But yeah this is going to be picked up by covid-deniers as more "proof" that covid is exaggarated.

I am not by any means a "covid-denier," but it seems to me this is evidence that the impact of Covid may be exaggerated. It's hard to say by how much (and I would be interested to learn if this is happening in US hospitals also).

Re: Over half of Covid hospitalisations tested positive after admission

#46

Post by cwp » Tue, Jul 27, 2021, 3:28 PM UTC

mavhc wrote: post #35

So their argument is: everyone is already infected, it's no big deal? Whereas the actual questions are: why are people going into hospital without having a Covid test first (assuming non emergency) And: What percentage of the people who tested positive in the previous 14 days in hospital because of Covid. And what percentage of the people who weren't tested went to hospital because of Covid related symptoms.

Yeah, those are the right questions. The point of the article is that people who go to the hospital for non-Covid reasons - eg, broken leg, heart attack, cancer - and then test positive are being counted as "hospitalized with Covid" even though they don't have a severe case.

So the statistics are being skewed. We don't really know by how much, because the article doesn't say how many went to the hospital for Covid-related symptoms.

Re: Over half of Covid hospitalisations tested positive after admission

#47

Post by ajsnigrutin » Tue, Jul 27, 2021, 3:31 PM UTC

CorrectHorseBat wrote: post #16

Since they will take up space in a covid ward, it's not that strange that they are counted as hospitalized by covid in some statistics.

But they will clear up spaces (and doctors and nurses) in other wards.

And they're hospitalized "with" covid and not "by" covid. They might even be asymptomatic, in the hospital because of a broken leg, and they count towards the statistics that we then use for new lockdowns.

Same with deaths "by" covid and deaths "from" covid. I know it's hard to say, when an 85yo patient with 6 different illnesses dies, if it was the covid that killed them or if it was unrelated heart failure.

There was even a time where once you tested positive for covid, you could only die from that, and nothing else: https://www.cebm.net/covid-19/why-no-one-can-ever-recover-fr...

> In summary, PHE’s definition of the daily death figures means that everyone who has ever had COVID at any time must die with COVID too. So, the COVID death toll in Britain up to July 2020 will eventually exceed 290k, if the follow-up of every test-positive patient is of long enough duration.

This was changed to 28 days (i think) later, but atleast having a soft separation of "with" "by" and "maybe/probably by" would also mean a lot.

Re: Over half of Covid hospitalisations tested positive after admission

#48

Post by jjgreen » Tue, Jul 27, 2021, 3:34 PM UTC

telesilla wrote: post #11

Is the Telegraph a paper of good repute? The article feels to me as somehow manipulative however I'm not local to the UK. I am wondering if this is propaganda or if these results are actually plausible.

It's a Tory (conservative) paper and always has been, traditional or reactionary depending on your point of view. Not sensationalist.

The Irish comic Dave Allen characterised the British press as follows:

One of the things about Britain, actually: you can always tell the way a person votes by the paper they read. For example, The Times is read by people who run the country. The Financial Times is read by people who own the country. The Daily Mail is read by the wives of the people who own and run the country. The Daily Mirror is read by the people who think they run the country. The Guardian is read by people who think that they should run the country. The Morning Star, or as it used to be known as, the Daily Worker is read by people who think that the country should be run by another country. The Daily Express is read by people who think that the country should be run as it was. The Daily Telegraph is read by people who think that it still is. And The Sun is read by people who don’t care who rules the country as long as they’ve got big boobs.

You get the idea

Re: Over half of Covid hospitalisations tested positive after admission

#49

Post by ajsnigrutin » Tue, Jul 27, 2021, 3:37 PM UTC

mavhc wrote: post #35

So their argument is: everyone is already infected, it's no big deal? Whereas the actual questions are: why are people going into hospital without having a Covid test first (assuming non emergency) And: What percentage of the people who tested positive in the previous 14 days in hospital because of Covid. And what percentage of the people who weren't tested went to hospital because of Covid related symptoms.

Re: Over half of Covid hospitalisations tested positive after admission

#50

Post by jaywalk » Tue, Jul 27, 2021, 3:37 PM UTC

raziel2p wrote: post #14

peteradio wrote: post #8

Comments so far seem to misunderstand the issue. People are not catching Covid in the hospital. They are in the hospital for non-covid reasons (broken leg, pink eye etc) but if they test positive it will show up in statistics as a "Covid Hospitalization". That is terribly misleading because we want to understand if Covid is causing an increase in hospitalizations, this is attributing other causes to Covid.

I mean, they may be catching covid in hospitals, there's no way to know for sure, but it seems unlikely to account for all these cases. But yeah this is going to be picked up by covid-deniers as more "proof" that covid is exaggarated.

I don't think "Covid deniers" make up any significant percentage of the population, but that doesn't change the fact that this is proof that Covid is exaggerated.