Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

Over half of Covid hospitalisations tested positive after admission

telegraph.co.uk

Post reply on HN
Print view View original

121–130 of 241 posts

Re: Over half of Covid hospitalisations tested positive after admission

#121

Post by naturalauction »

beerandt wrote: post #68
mizzack wrote: post #39

Earlier quoted context omitted.

> 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…

On inauguration day.

Is there evidence that the cdc/other testing labs significantly changed their protocols as a result of this new advice?

Re: Over half of Covid hospitalisations tested positive after admission

#122

Post by aeternum »

cameldrv wrote: post #90
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…

At the latest low point in the epidemic, some areas were seeing test positivity rates of under 0.5%. If false positives were a large portion of positives, this would seem to be impossible.

The problem is the false positive isn't truly independent of environmental factors.

PCR determines how many exponential amplifications are necessary to get a detectable amount of the target RNA sequences.

The amount of that target RNA floating around in the environment does slightly impact the base amount present in even covid-negative patients.

Re: Over half of Covid hospitalisations tested positive after admission

#124

Post by cameldrv »

aeternum wrote: post #122
cameldrv wrote: post #90

Earlier quoted context omitted.

At the latest low point in the epidemic, some areas were seeing test positivity rates of under 0.5%. If false positives were a large portion of positives, this would seem to be impossible.

The problem is the false positive isn't truly independent of environmental factors. PCR determines how many exponential amplifications are necessary to get a detectable amount of the target RNA sequences. The amount of that target RNA floating around in the environment does slightly impact the base amount present in even covid-negative patients.

It's true that people who had COVID can still have viral RNA in their noses for a while and still test positive.

The most sensitive tests have a limit of detection of a couple hundred copies/ml, and the collection kits usually use 1ml of VTM or equivalent. I find it hard to believe that a significant number of people will have enough viral RNA in their nose to put hundreds of copies onto a swab unless it's their own body that's producing those copies.

Re: Over half of Covid hospitalisations tested positive after admission

#125

Post by cameldrv »

dragonwriter wrote: post #93
cameldrv wrote: post #90

Earlier quoted context omitted.

At the latest low point in the epidemic, some areas were seeing test positivity rates of under 0.5%. If false positives were a large portion of positives, this would seem to be impossible.

> At the latest low point in the epidemic, some areas were seeing test positivity rates of under 0.5%. If false positives were a large portion of positives, this would seem to be impossible. Its quite possible, especially if there is a testing bias toward people who are less likely to have the disease

Even if they were testing people that were all externally known not to have COVID, if only 0.5% of people are testing positive, that's the false positive rate.

All the data we have indicates that false positives on PCR are extremely rare. The only place it gets fuzzy is the definition of positive. People who were previously infected can test positive, and people with very mild infections can also test positive. People who have never been infected though essentially do not test positive.

Re: Over half of Covid hospitalisations tested positive after admission

#126

Post by dm319 »

polytely wrote: post #112
dm319 wrote: post #81

I am weary of this newspaper's reporting - they wage a continual war on the NHS, and they seem to have some writers paid to continually put out negative news on the NHS. Two points: 1. COVID-19 is the most thrombogenic infectious disease known to man. It likely has a serious impact on co-morbidities in a way that hasn't been clearly studied yet. This means it's likely to exacerbate current conditions. 2. Hospitals ar…

2. Isn't that from all the rescheduled surgeries and such? I know that here in the Netherlands there is still a huge backlog of care that couldn't happen when the hospitals were full, that has to be caught up on.

Sadly the rescheduled care is getting cancelled due to lack of ITU beds for post-surgery. I don't know what's going, but there seems to be a backlog of complaints that people are only now getting investigated, and with increased social mixing I guess infectious diseases are going up. Still, it's a bit strange to be this overwhelmed at this time if year.

Re: Over half of Covid hospitalisations tested positive after admission

#127

Post by dm319 »

robocat wrote: post #103
dm319 wrote: post #81

I am weary of this newspaper's reporting - they wage a continual war on the NHS, and they seem to have some writers paid to continually put out negative news on the NHS. Two points: 1. COVID-19 is the most thrombogenic infectious disease known to man. It likely has a serious impact on co-morbidities in a way that hasn't been clearly studied yet. This means it's likely to exacerbate current conditions. 2. Hospitals ar…

> Hospitals are full in the UK at the moment. New Zealand hospitals have been in “crisis” pretty much all year, and we have no Covid. Currently it is due to a respiratory virus called RSV, but there were severe problems in other months too, not due to RSV. https://www.google.co.nz/search?q=nz+hospitals+overrun+OR+cr...

Yes, I think other (non-covid) infectious diseases are partly to blame. They also have a knock on effect for other conditions like coronary heart disease, COPD and dementia, etc.

Re: Over half of Covid hospitalisations tested positive after admission

#128

Post by ianhawes »

forcry wrote: post #114
ianhawes wrote: post #99

Earlier quoted context omitted.

Prior to the vaccine rollout (at least in the US), positive cases were used as a metric for public health officials to gauge whether the virus was spreading, whether containment efforts were effective, and how to manage the presumable change in hospitalizations and fatalities. As vaccination efforts have rolled out, there is still a relationship between positive cases and deaths, however the ratio of cases to deaths…

>The only metric the public should be concerned about is whether they have or have not been vaccinated. That would be quite stupid. Because if the risk of the disease is low, vaccines does not make sense when you do risk/benefit calculation. Hence the people should know about the cases. Of course, instead, if you are looking to push vaccines no matter what, you would say something like >The only metric the public sho…

> That would be quite stupid. Because if the risk of the disease is low, vaccines does not make sense when you do risk/benefit calculation.

The risk of symptomatic illness is low if you are vaccinated. The risk of symptomatic illness is high if you are unvaccinated. The risk of death is high if you are unvaccinated and have pre-existing conditions and are under the age of 65. The risk of death is very high if you are unvaccinated and over the age of 65.

Re: Over half of Covid hospitalisations tested positive after admission

#129

Post by hackeraccount »

jjgreen wrote: post #48
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 o…

Wasn't that in Yes, Minister? Or was it a shorter version... it's been awhile since I saw that show but that's almost the only joke a remember distinctly. Oh, that and the line, "If you want to stab someone in the back you first need to get behind them," which I reference not infrequently.

Re: Over half of Covid hospitalisations tested positive after admission

#130

Post by beerandt »

pavon wrote: post #56

> Experts said it meant the national statistics, published daily on the government website and frequently referred to by ministers, may far overstate the levels of pressures on the NHS. I don't understand this part. Isn't the important number here the total number of people in the hospital (or ICU or other ward) relative to the total number that the hospital (or ICU or other ward) can accommodate? Or alternatively, t…

"Available" beds/ hospital capacity is usually a floating number, and it's not an absolute capacity, it's just the instant capacity at that moment. It changes in response to demand.

Hospitals don't count closed wards/wings/floors that can be staffed and "activated." Same goes for converting other areas/depts of the hospital to covid units. Which is why it's better to monitor absolute cases or deaths, not % "capacity".

Post reply on HN