Coronavirus - worldwide spread and control

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FMMM1 said:
As @Jonathan Edwards has said this is a % game.

So if your 90% right, and R naught reduces to less than 1, then the outbreak cannot be sustained.

On the other hand sitting on your ass and doing nothing, since the test isn't 100%, well you can see the results in the UK.

Presumably you'd also pick up the positive health care worker*/positive member of the public via contact tracing --- oh if you did it!

*EDIT: The changes of two consecutive tests giving false negative (if the test is 90% accurate) would be 0.1 X 0.1 i.e. 1 in a hundred.
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No-one is sitting on their ass.

On the other hand imagine this.

Public/media pressure results in such political pressure that governments worldwide decide they have no alternative to go for mass population testing in some sort of numbers game where everyone tries to match or exceed what Germany had been doing.

We know there is already a worldwide shortage of the necessary testing materials. How long will they last if everyone decides to do mass testing?

You would soon be in the position where you can't even test key sector workers and what will the result then be?
 
sars-cov-2-viral-load-and-the-severity-of-covid-19
Oxford COVID-19 Evidence Service Team, Centre for Evidence Based Medicine, march 26th.
not peer-reviewed


The evidence suggests an association of viral dose with the severity of the disease. However, the evidence of the relationship is limited by the poor quality of many of the studies, the retrospective nature of the studies, small sample sizes and the potential problem with selection bias.
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They look also at SARS-co-1 and Influenza. Influenza:
... 1918-19 Spanish Flu pandemic. Simulation models showed that the infectious dose was related to the number of simultaneous contacts a susceptible person has with infectious ones; that severe cases of influenza result from higher infectious doses of the virus; and over-crowded places are the ideal environment for a susceptible person to be exposed to very high infectious doses of influenza.

  • High infectious dose and influenza disease progression have been shown in experimental animals;
  • The high infectious dose is associated with a higher viral load; and
  • The high infectious dose is associated with a smaller period of time to maximum viral load. [2]
[2] Influenza Infectious Dose May Explain the High Mortality of the Second and Third Wave of 1918–1919 Influenza Pandemic.
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Healthcare Workers
Reports across several countries report healthcare workers are more at risk of catching SARS-CoV-2 and potentially more severe. having COVID-19 disease. We use multiple sources as there is considerable variation in the number of deaths reported, which currently presents a confusing picture.
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A detailed list of available information follows.
 
Marco said:
We know there is already a worldwide shortage of the necessary testing materials. How long will they last if everyone decides to do mass testing?
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Do we know this? It is not what my laboratory colleagues (such as my nephew Al who goes on TV to talk about these things) have been telling me. They have been wanting to help for weeks but government has shown little interest. Even I have been asked to help to get round bureaucratic blockages but I was not qualified to do so.

I think now is not the best time to try to roll out indiscriminate testing because hopefully we are the peak of infection rates. The testing should never have been curtailed earlier on. It will be badly needed once the peak has turned. But even so we need far more targeted testing right now - of health and care home workers.

If 90% of tests are coming back negative then the test is not being overused. Tests of this sort should be picking up percentages of that sort if they are going to tease out the real cases in the way needed.

I am sorry to disagree but people have very definitely been sitting on their arses for two months now.
 
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Marco said:
Not necessarily. There are negative consequences where you have a relatively small percentage of the population currently infected and a test with an approximate 10% error rate.

Imagine quarantining 10% of healthcare workers due to false positives or conversersely releasing 10% of infected cases back into the community due to false negatives.

A hypothetical example :

The perils of mass coronavirus testing

https://www.aei.org/articles/the-perils-of-mass-coronavirus-testing/
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I read somewhere that the Chinese were doing multiple tests on people. I don't know if test failures are independent?
 
Jonathan Edwards said:
If 90% of tests are coming back negative then the test is not being overused. Tests of this sort should be picking up percentages of that sort if they are going to tease out the real cases in the way needed.
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I would have thought if 90% of tests are coming back positive then this doesn't give much info as you are testing those you have a strong belief are ill. We need to be testing those who are in contact with people who are ill to avoid further transmission. If tests are limited shouldn't we test those who come into contact with a lot of people who may then spread the disease and before they are symptomatic rather than those who have clear symptoms?
 
Marco said:
No-one is sitting on their ass.

On the other hand imagine this.

Public/media pressure results in such political pressure that governments worldwide decide they have no alternative to go for mass population testing in some sort of numbers game where everyone tries to match or exceed what Germany had been doing.

We know there is already a worldwide shortage of the necessary testing materials. How long will they last if everyone decides to do mass testing?

You would soon be in the position where you can't even test key sector workers and what will the result then be?
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Regarding "No-one is sitting on their ass". I live in the UK and I can assure you that I do not believe the Government is delivering testing for health care workers or members of the public who are demonstrating symptoms of the disease are i.e. are infections. They seem to have decided not to suppress the outbreak by testing those with symptoms, isolating those infected (reducing transmission). Policy has not changed -- we'll see about delivery.

I'm not suggesting that if tests are limited then everyone has equal priority. E.g. in the Republic of Ireland health care workers have priority i.e. to keep the health care system functioning.

The other thing is that if you are concerned about false positives, then test the positives with a second (preferably different/more accurate) test.

I hadn't read the article you provided a link to i.e. when I responded earlier; I've only scanned it and it looks OK. However, the WHO recommends test, isolate, trace contacts, reduce transmission is this paper consistent with that message?

Economics, and lots of Government handouts, will mean that supply of reagents (to test health care workers and the public) will eventually match the high demand. Similarly the number of ventilators and hopefully drugs and a vaccine. We seem to be in the hunkering down stage.

Some countries are well behind --- I live in the UK not Germany, South Korea ---.

@Marco have you seen the coverage of the different outcomes in Lombardy compared to Veneto?
 
Adrian said:
I would have thought if 90% of tests are coming back positive then this doesn't give much info as you are testing those you have a strong belief are ill. We need to be testing those who are in contact with people who are ill to avoid further transmission. If tests are limited shouldn't we test those who come into contact with a lot of people who may then spread the disease and before they are symptomatic rather than those who have clear symptoms?
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Agree with all of that.
 
Adrian said:
I read somewhere that the Chinese were doing multiple tests on people. I don't know if test failures are independent?
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If they are sampled separately, test failures should be somewhat independent.

Excluding contamination, RTPCR should be over 99% specific, so the numbers in the AEI example only really apply to other testing methods, such as serology - which would lead to very high false positive numbers if used for large fractions of the asymptomatic population.
 
Jonathan Edwards said:
Do we know this? It is not what my laboratory colleagues (such as my nephew Al who goes on TV to talk about these things) have been telling me. They have been wanting to help for weeks but government has shown little interest. Even I have been asked to help to get round bureaucratic blockages but I was not qualified to do so.

I think now is not the best time to try to roll out indiscriminate testing because hopefully we are the peak of infection rates. The testing should never have been curtailed earlier on. It will be badly needed once the peak has turned. But even so we need far more targeted testing right now - of health and care home workers.

If 90% of tests are coming back negative then the test is not being overused. Tests of this sort should be picking up percentages of that sort if they are going to tease out the real cases in the way needed.

I am sorry to disagree but people have very definitely been sitting on their arses for two months now.
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I can only go by the shortages of reagents, swabs etc being widely reported in many countries although it does appear, in a UK context at least, that small labs were ready and willing to pitch in except PHE bureaucracy prevented them from doing so.

At least we're agreed that now is not the time for rolling out indiscriminate testing - but this is still what the media keep pushing as if numbers are all that matter.

As for what should have been done - this is debatable - but I'm more concerned about what needs to be done in the coming few weeks.

While decorating yesterday (I stocked up on materials before the lockdown) I was shocked listening on the radio to the Northern Ireland health minister who sounded close to tears. They expect numbers to peak in the next two weeks with approx 500 hospital admissions per week. NI currently has 150 ventilators and the minister was 'praying to god' they could ramp up provision in time.

His response to questions regarding other 'controversial' aspects of the government response was that he 'was too busy trying to save lives to play politics'.

I'd rather government's were allowed to
 
I wonder whether it would be a good idea for government ministers who are not scientists to not be presented with graphs with a logarithmic vertical scale. It's all too easy to look at the straight line or even decrease, and imagine that means numbers of cases and deaths are falling. They say a picture tells a thousand words. I doubt whether some in government have the brainpower to get that a straight line on a log scale means exponential growth.
 
Just some thoughts reading all this. Firstly, here in Scotland health care workers are being tested. Before all this started, coronavirus was tested as part of a general screening that included flu and other respiratory viruses. If the test was positive and it was clinically necessary the sample was sent to one of 2 centres who tested for the actual coronavirus it was. (The same thing is done for enteroviral species) Once the pandemic started our local lab began doing the specific Covid19 PCR.

Now they are trying out cartridges which will be used at point of care and look for IgM which will show a current infection and IgG which will show a past infection (broadly speaking) The value of that test is that it gives a result much, much faster than PCR.

As it stands, PCR takes 24 48 hours to give a result. You can't wait that long before you start treating a patient so they must all be considered positive. That is why self isolating as if you were positive has to be started before PCR results. When there is a shortage of kits, self isolating without being tested makes sense. The exception is key workers and that is why Scotland is testing them.

I am too cognitively challenged to consider what the government did or should be doing, but the reasons for testing are mixed and articles and statements seem to be getting them all mixed up (it may be me trying to understand)

There is patient care first and foremost.
Care for medical personnel and other key workers.
Testing and isolating contacts. Very important at the start of an outbreak and now, people will really believe in the disease if they have a positive test.
Then there is epidemiology to give us the data to understand the virus and how it spreads. This data should inform policy and will be vital for the future.

One of the articles said that the problem with logarithmic emergencies was that the time to act was at the very beginning but then people assume it was never much a crisis at all. If you avert a disaster no one thinks there would have been one.

That happened with the millennium bug where planes didn't fall out of the sky and civilization collapse, well things stopped working, because of the amount of time, effort and money that went into fixing it.

Then there was the swine flu epidemic where people decided it was a plot to sell tamiflu and trick people into getting vaccinated.

The one thing we can be certain of for the future is that there are going to be years of recriminations no matter which government and what they decided to do.
 
We’re not even in proper lockdown yet but some are wanting to get out of it ASAP. The options for the UK’s exit strategy are Whitty and Valance’s biggest concerns at the moment.

“There are high-level concerns that devastating economic consequences will be seen sooner than previously thought. Johnson and the chancellor Rishi Sunak are said to be especially concerned about this outcome, along with some ministers and aides on the libertarian wing of the Tory party dubbed the “Spectator set” by colleagues who want to keep the lockdown in place.”



 
Because there is a close relationship between the north of Italy and Wuhan (making fashion and clothes) the scenario of how the virus developed might be a bit more complicate.

Maybe the virus comes from China (and its bats), but maybe the virus found in the north of Italy the best environment to prosper (air pollution, an aged population) and to possibly further mutate. And this might have been taken place already in November of last year or even before (and now materializes in a visible manner).

I don´t know how likely this or any related scenario is. In the comments of the following youtube video are some more speculations. Nephrologist Prof Giuseppe Remuzzi shared his observation of unusual pneumonia in the north of Italy in november of 2019. Hope its no fake.



A Chinese newspaper on this issue:
https://www.scmp.com/news/china/soc...ange-pneumonia-seen-lombardy-november-leading
 
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FMMM1 said:
Regarding "No-one is sitting on their ass". I live in the UK and I can assure you that I do not believe the Government is delivering testing for health care workers or members of the public who are demonstrating symptoms of the disease are i.e. are infections. They seem to have decided not to suppress the outbreak by testing those with symptoms, isolating those infected (reducing transmission). Policy has not changed -- we'll see about delivery.
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For what it's worth I was listening to local radio yesterday (BBC Radio Ulster Nolan show) and with regards to testing it was anecdote,anecdote, anecdote followed by a complete rebuttal from the chief medic.

I'm not suggesting that if tests are limited then everyone has equal priority. E.g. in the Republic of Ireland health care workers have priority i.e. to keep the health care system functioning.
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Unfortunately testing in ROI appears to have been quite chaotic even if well intentioned :

First we were too restrictive with testing, denying people tests simply because they had not been abroad.

Then we were too liberal, and the system was flooded by the “worried well”. So we changed the criteria again, and thousands had their tests cancelled.

All along the process has been marred by delays in getting a test, having it processed and reported back. These delays were understandable, but still reduce the likelihood of compliance, and are likely to lead to more false negatives.
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https://sluggerotoole.com/2020/03/3...northern-ireland-need-more-searching-inquiry/

Economics, and lots of Government handouts, will mean that supply of reagents (to test health care workers and the public) will eventually match the high demand. Similarly the number of ventilators and hopefully drugs and a vaccine. We seem to be in the hunkering down stage.
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Agreed.

@Marco have you seen the coverage of the different outcomes in Lombardy compared to Veneto?
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I have. I just don't think there's enough information there on which to base any judgement.
 
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