MERS Coronavirus warning

The way they are used LFD’s are incredibly useful. They need a higher level of antigens to generate a positive than a PCR, but at the level at which a person starts to get infectious.

They definitely are not perfect (especially in those who gag easily and might not carry out the test correctly as a result) but they are a useful part of the Swiss Cheese model.

False positives on their own can be a cause for concern for some - but when viewed as part of the wider use of Non-Pharmaceutical Interventions AND the vaccine campaign LFD’s are incredibly useful.
According to the Guardian article posted earlier, the value of LFD's diminishes with low infection rates, to the point that the relative number of false positives starts to become a burden.
 
Are you suggesting that this is deliberate policy? That more accurate data would not have been welcome because it was not politically useful?

Kind of is.

You say politically useful, I say expedient. They are synonyms.

No. This is what I say. The data is the best available given the novelty of the virus and is improved when possible and revised if necessary. The politicians may or may not be tailoring their messages in light of these changes.

You are suggesting that the figures were and are a work of fiction produced with the aim of manipulation rather than managing the mitigation of the pandemic.
 
According to the Guardian article posted earlier, the value of LFD's diminishes with low infection rates, to the point that the relative number of false positives starts to become a burden.
A very low rate of low positives is not a problem I don’t think - and if this is found to be correct in areas of low infection rate then you can always bring back confirmatory PCR testing to weed this out (If not already being done or considered)
The Guardian does spin things a certain way and has been guilty of lying through omission (from personal experience).
 
A very low rate of low positives is not a problem I don’t think - and if this is found to be correct in areas of low infection rate then you can always bring back confirmatory PCR testing to weed this out (If not already being done or considered)
The Guardian does spin things a certain way and has been guilty of lying through omission (from personal experience).
Surely it depends on the comparative rate of false positives given by the test to the actual rate of infection.

Deeks says that at a lower prevalence (0.5%), around half of positive tests would be false positives, “which would indicate that half of the children, teachers, families, and their bubbles being asked to isolate this week are doing so unnecessarily.
 

Arse_Bandit

Old-Salt
Surely it depends on the comparative rate of false positives given by the test to the actual rate of infection.

Deeks says that at a lower prevalence (0.5%), around half of positive tests would be false positives, “which would indicate that half of the children, teachers, families, and their bubbles being asked to isolate this week are doing so unnecessarily.
I'm not sure this is true, the one (false) positive we had was immeadiately followed up with a PCR so they were only out of school for a day.

ETA What I mean is there's likely not a consistant policy, some areas/schools might not be as pragmatic as our school/area. I know if the follow up PCR was positive for example, the whole bubble was asked to remain at home (planned anyway, as it turned out no-one has been positive-positive yet)
 
Surely it depends on the comparative rate of false positives given by the test to the actual rate of infection.

Deeks says that at a lower prevalence (0.5%), around half of positive tests would be false positives, “which would indicate that half of the children, teachers, families, and their bubbles being asked to isolate this week are doing so unnecessarily.
the government brought back confirmatory testing using PCR tests on 31 March 2021 due to VOC. See my comment above re: Guardian omitting stuff.

“If the population being tested has 0.5% prevalence and the specificity of the antigen LFD test is 99.5% then:

  • a test with 50% sensitivity would detect 25 true positive cases, 25 false negatives (people who would be positive on PCR but negative on the LFD) and 50 false positive cases per 10,000 people tested
  • with 70% sensitivity you will have 35 true positive cases, 15 false negatives on antigen LFD and 50 false positive cases per 10,000 people tested
  • with 90% sensitivity you will have 45 true positive cases, 5 false negatives and 50 false positive cases on antigen LFD per 10,000 people tested
Ongoing review in real time for the ‘Innova SARS-CoV-2 Antigen Rapid Qualitative Test’shows that the test had a specificity of 99.68% (that is, a false-positive rate of 0.32%), an overall sensitivity of 76.8%, and a sensitivity of over 95% for those with high viral loads.”

Souce: Evidence summary for lateral flow devices (LFD) in relation to care homes
 

Chef

LE
No. This is what I say. The data is the best available given the novelty of the virus and is improved when possible and revised if necessary. The politicians may or may not be tailoring their messages in light of these changes.

You are suggesting that the figures were and are a work of fiction produced with the aim of manipulation rather than managing the mitigation of the pandemic.
I'm not saying they make them up, I'd go with 'tailoring their messages'.

However I can't stand here violently agreeing with you all day, I've got supper to finish cooking :)
 
Indeed, it's the reason that UK schools have been throwing boxes of them at staff and students. With a large enough sample size they should be effective.

For example - an outbreak infects 20 kids in a class. Half of them forget to do a test which leaves 10. Half of them do the test incorrectly which leaves 5. Of the ones who did the test correctly half of those return a false negative so there are still 2 positive test results to quarantine those individuals and anyone they've been near.

Numbers picked off the top of my head except for the 50% false negative rate which was a good estimate a month ago but there may be a more accurate number now.

How useful they will be on an individual basis is much more questionable.
The rapid tests are not useful on an individual level unless you are so short of PCR capacity and infection so widespread that any test might be better than no test at all.

The biggest problem with the rapid tests is that if you test negative that doesn't necessarily mean you aren't infected. If you test a group of people who closely associate with one another though, then odds are that if several of them are infected and infectious, that is, you have an outbreak in its early stages, then at least one of tests will pick it up. That can then be followed up with PCR tests to see who is actually infected and who isn't.

The key is going to be the ability to quickly follow up with PCR tests.

The way that infection mostly spreads isn't by one person infecting two people who then each infect two others, etc. On average that's how it works out mathematically, but the actual chain goes more like one person infects 20 people but only a few of those people go on to infect anyone else, but when they do they also each infect another 20, etc.

If those events can be nipped in the bud then these infection events can be stopped before they get too far. Testing is a great tool for that, and rapid tests can be useful as more people are associating more with each other.

A very slick testing system can be a tool which, in combination with other measures as well as vaccination, can be used to keep outbreak events localised. That in turn means we can ease off on lockdown.

Another way of putting it is that if your testing and tracing system is good enough and quick enough, and you are starting from a low enough level of infection, you won't need another lockdown. This is what was tried early on when the pandemic started, but the virus was so infectious that it outran the then existing testing and tracing capacity. Testing and tracing has been since beefed up, and fewer people are likely to pass on infection as they are vaccinated (which reduces although not eliminates their ability to transmit the virus), so it may be a more successful strategy now.

So, the rapid tests are another tool in the tool box, but they only work when being used for the right purposes.
 
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The problem with the LFT is explained in that article linked to in post #22246.

The proportion of false positives – people incorrectly told they have the virus – increases when the prevalence of the disease falls. This happens because although the number of true positives is falling, the tests produce roughly the same number of false positives – meaning the proportion of incorrect results becomes greater.

So the ratio of false positives increases with the inverse of the real infection rate. In early February they would have looked quite effective, not so much now.
The rapid tests are useful as a monitoring tool when used in the right circumstances. However, they give both false positives and false negatives. What they are mainly useful for is as a trigger for telling you that PCR tests are needed on a group of people who closely associate.

By allowing you to pick out groups of people who need to isolate while waiting for PCR test results, it helps reduce the need for all of society to go into lockdown. Or to put it another way, an inconvenience for a small number of people is better than lockdown for everyone once the horse is well and truly out of the barn.

At some point when the number of vaccinations is high enough and the incidence of infection low enough, then the inconvenience caused by the tests will be outweighed by their decreasing usefulness and they can be discontinued.

There are companies working on small bench top PCR test machines that can be used in schools, care homes, workplaces, and the like. They give results in something like 20 minutes. I'm not aware of any which are ready for the market though. If they were widely available now, then they could be used to give follow-up PCR tests on the spot instead of taking however long it takes currently. Perhaps those will be ready in time for the next pandemic.
 
Had a few socially distanced beers with the gang from work tonight ,freezing cold ! I was disappointed to realise I'm not the ice cold lone wolf of lockdown warrior I'd imagined .It Was nice to have some social semi drunk buffoonery with work mates and acquaintances seemed very strange to begin with, as usual people drank and began to lapse into 'the old ways' I left as it started to get silly but I'm as guilty as anyone as I was there . Hope none of us regret it . Pub staff and customers were all behaving well for humans ,but I can't imagine there Will not be a spike/surge and deaths from about the 25th and on. Very nice from a human social point of view but objectively a bit of a worry . Got home left all my clothes in the conservatory and had a shower. In bed fretting now! Pubs eat money !
 
Had a few socially distanced beers with the gang from work tonight ,freezing cold ! I was disappointed to realise I'm not the ice cold lone wolf of lockdown warrior I'd imagined .It Was nice to have some social semi drunk buffoonery with work mates and acquaintances seemed very strange to begin with, as usual people drank and began to lapse into 'the old ways' I left as it started to get silly but I'm as guilty as anyone as I was there . Hope none of us regret it . Pub staff and customers were all behaving well for humans ,but I can't imagine there Will not be a spike/surge and deaths from about the 25th and on. Very nice from a human social point of view but objectively a bit of a worry . Got home left all my clothes in the conservatory and had a shower. In bed fretting now! Pubs eat money !

I do hope nothing comes of it and you stay healthy. Just in case though what size boots?
 
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PappaBear08

Old-Salt
From what I have read the excess deaths numbers are still a bit fuzzy. Since it wasn't a "normal" year, people aren't sure if the "normal" number of deaths expected each year should apply or whether adjustment factors need to be applied. For example, is staying home safer than going to work, or is it more dangerous because people tend to do more stupid things while at home? That affects the baseline of the "normal" death rate before you throw COVID-19 into the equation.

I suspect this will be debated for some time before a consensus is reached.

Apologies for the late reply

Isn't it all based around the 5 year average, so the expectation of the number of deaths is simply the 5 year average figure? If you look at flu deaths for example, over the last 20 years the numbers have varied wildly so there is no "normal" number beyond the 5 year average AIUI.

Given that no-one has died of Flu since last March, RTC deaths are down, workplace deaths are down, and other causes are up, etc etc - why not KISS knowing that the deep dive into the specifics will happen down the line?

The all cause mortality excess death numbers at least include pandemic deaths not otherwise counted (a number of suicides, ill health never treated, cessation of treatments as priorities change, stroke and cardiac based on stress/sedentary furlough followed by manic return to work, DIY accidents etc) and taking the figures over the year would also account for those who would likely have checked out due to flu etc but got clobbered by the rona first... it doesn't matter whether work or home is safer as dead is dead and therefore counted.

I don't think the home/work thing affects the numbers, certainly not to the point of any adjustment in all cause mortality - probably just a footnote on future chart usage for the ACM data, however when they start to dig into the with/from Covid deaths and the 2nd/3rd order effects we may get more usable data for specific causes but it still doesn't change the ACM figures.
At least this way the NHS and the various flavours of Westminster Sh*tweasel, CS, and the media get their comparison as any political manipulation of the logged covid deaths is shown for what it is and the different criteria from different nations can be disregarded for the ACM.

Just my 2p.
 
Apologies for the late reply

Isn't it all based around the 5 year average, so the expectation of the number of deaths is simply the 5 year average figure? If you look at flu deaths for example, over the last 20 years the numbers have varied wildly so there is no "normal" number beyond the 5 year average AIUI.

Given that no-one has died of Flu since last March, RTC deaths are down, workplace deaths are down, and other causes are up, etc etc - why not KISS knowing that the deep dive into the specifics will happen down the line?

The all cause mortality excess death numbers at least include pandemic deaths not otherwise counted (a number of suicides, ill health never treated, cessation of treatments as priorities change, stroke and cardiac based on stress/sedentary furlough followed by manic return to work, DIY accidents etc) and taking the figures over the year would also account for those who would likely have checked out due to flu etc but got clobbered by the rona first... it doesn't matter whether work or home is safer as dead is dead and therefore counted.

I don't think the home/work thing affects the numbers, certainly not to the point of any adjustment in all cause mortality - probably just a footnote on future chart usage for the ACM data, however when they start to dig into the with/from Covid deaths and the 2nd/3rd order effects we may get more usable data for specific causes but it still doesn't change the ACM figures.
At least this way the NHS and the various flavours of Westminster Sh*tweasel, CS, and the media get their comparison as any political manipulation of the logged covid deaths is shown for what it is and the different criteria from different nations can be disregarded for the ACM.

Just my 2p.
I think the point is that people will argue back and forth over how to count the number of COVID-19 deaths because of the factors you listed. If for example more people die from DIY accidents because they had to stay home, are those COVID-19 deaths? If not then we need to subtract those from the excess deaths totals if we want to find out how many people died from COVID-19 but were never diagnosed as having had COVID-19 due to lack of testing or some other reason.

If more people didn't die from flu, that reduces the overall rate of death that we would see in a normal year. How do we account for that, or should we?

You might have an opinion on this, but someone else might have a different opinion. These are the sorts of questions that will have to be thrashed out before a consensus is reached however.

Furthermore, since we were talking about international comparisons, what happens when other countries decide to adjust their numbers to take these sorts of factors into the account, but do so in a way that is different from how the UK or other countries do it. Someone will have to go through the raw data for each country and account for all of this before we can compare one country to another. That will be neither simpler nor easy.

That's why I said it will take a while after to come up with a conclusive answer, and ever then it will only be a good estimate.
 
Here's the COVID-19 summary for Friday.
Coronavirus: What's happening in Canada and around the world on Friday

In Canada, the province of Ontario have extended the stay at home order to 6 weeks from 4. Also, provincial borders with Quebec and Manitoba are closed to non-essential travel. Police will have new powers to enforce the stay at home order.
Ontario Solicitor General Sylvia Jones said the changes along the provincial borders would take effect at 12:01 a.m. on Monday. Jones said incoming travellers not meeting a list of prescribed exceptions will be turned back. Quebec has since signalled the province will be closed to travellers coming in from Ontario.

The province will also extend an existing stay-at-home order to last six weeks, instead of the planned four.

Ontario is also giving police new powers to enforce public health orders, allowing officers to ask anyone outside their residence to indicate their purpose for leaving home and to provide their address. That includes stopping vehicles. The new police measures drew immediate condemnation from civil liberties activists.

Moderna are cutting their supplies of vaccine to Canada in half due to QA backlogs in Europe. However Pfizer-Biontech are increasing their shipments. Canada has been relying on these two vaccines, as supplies of the Oxford-AstraZeneca vaccine are very limited and none of the Johnson & Johnson (Janssen) vaccine has arrived yet.
After word earlier Friday that Canada's incoming vaccine supply from Moderna will be slashed in half through the rest of April, Prime Minister Justin Trudeau said Ottawa signed an agreement with Pfizer for additional doses of its COVID-19 vaccine.

He said Pfizer will deliver four million additional doses in May, two million additional doses in June and two million more in July.

Trudeau said for next month alone, the number of Pfizer doses will be double what Canada was expecting.


Globally, infection rates are increasing. The WHO have said that daily case rates around the world have doubled.
"Globally, the number of new cases per week has nearly doubled over the past two months. This is approaching the highest rate of infection that we have seen so far," Tedros Adhanom Ghebreyesus said.

Germany are debating giving the federal government more powers to enforce lockdowns nationally. Normally these are handed at the provincial level.
In Europe, German Chancellor Angela Merkel urged legislators Friday to approve new powers that would allow her to force lockdowns and curfews on areas with high infection rates.

This is happening while Germany saw 25,831 new cases and 247 new deaths.
Her speech came as the country recorded 25,831 new cases of COVID-19 overnight and 247 additional deaths.

Indian reported 217,353 new cases and 1,185 new deaths. They have now closed tourist sites for a month, including the Taj Mahal.
In Asia, India closed museums and tourist sites on Friday, including the iconic Taj Mahal, for a month to curb the country's second coronavirus wave.

India's 217,353 new cases marked the eighth record daily increase in nine days and took total cases to nearly 14.3 million. India's case count is second only to the United States, which has reported more than 31 million infections.

Deaths from COVID-19 in India rose by 1,185 over the past 24 hours — the highest single-day rise in seven months — to reach a total of 174,308, the health ministry reported.

South Africa have started taking registrations for vaccinating the elderly beginning next month. They have been focusing on vaccinating health care workers until now, something which is still not complete.
In Africa, South Africa took the first step in its mass vaccination campaign on Friday by starting online registrations for the elderly to receive shots beginning next month.

South Africa's inoculation drive is dependent upon millions of Pfizer vaccine doses arriving in the country within weeks. So far, South Africa has vaccinated 290,000 of its 1.2 million health-care workers with the Johnson & Johnson vaccine.
 

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