Modelovanje epidemije i dugoročne procene njenog kretanja

[Lord Protector]

Da, i najverovatnije je u pravu...

 

 

 

 

[vememah]

Quote

Opinion

Coronavirus outbreak

The UK's coronavirus policy may sound scientific. It isn't

Nassim Nicholas Taleb and Yaneer Bar-Yam

Dominic Cummings loves to theorise about complexity, but he’s getting it all wrong

When, along with applied systems scientist Dr Joe Norman, we first reacted to coronavirus on 25 January with the publication of an academic note urging caution, the virus had reportedly infected fewer than 2,000 people worldwide and fewer than 60 people were dead. That number need not have been so high.

At the time of writing, the numbers are 351,000 and 15,000 respectively. Our research did not use any complicated model with a vast number of variables, no more than someone watching an avalanche heading in their direction calls for complicated statistical models to see if they need to get out of the way.

We called for a simple exercise of the precautionary principle in a domain where it mattered: interconnected complex systems have some attributes that allow some things to cascade out of control, delivering extreme outcomes. Enact robust measures that would have been, at the time, of small cost: constrain mobility. Immediately. Later, we invoked a rapid investment in preparedness: tests, hospital capacity, means to treat patients. Just in case, you know. Things can happen.

The error in the UK is on two levels. Modelling and policymaking.

First, at the modelling level, the government relied at all stages on epidemiological models that were designed to show us roughly what happens when a preselected set of actions are made, and not what we should make happen, and how.

The modellers use hypotheses/assumptions, which they then feed into models, and use to draw conclusions and make policy recommendations. Critically, they do not produce an error rate. What if these assumptions are wrong? Have they been tested? The answer is often no. For academic papers, this is fine. Flawed theories can provoke discussion. Risk management – like wisdom – requires robustness in models.

But if we base our pandemic response plans on flawed academic models, people die. And they will.

This was the case with the disastrous “herd immunity” thesis. The idea behind herd immunity was that the outbreak would stop if enough people got sick and gained immunity. Once a critical mass of young people gained immunity, so the epidemiological modellers told us, vulnerable populations (old and sick people) would be protected. Of course, this idea was nothing more than a dressed-up version of the “just do nothing” approach.

Individuals and scientists around the world immediately pointed out the obvious flaws: there’s no way to ensure only young people get infected; you need 60-70% of the population to be infected and recover to have a shot at herd immunity, and there aren’t that many young and healthy people in the UK, or anywhere. Moreover, many young people have severe cases of the disease, overloading healthcare systems, and a not-so-small number of them die. It is not a free ride.

This doesn’t even include the possibility, already suspected in some cases, of reccurrence of the disease. Immunity may not even be reliable for this virus.

Worse, it did not take into account that the duration of hospitalisation can be lengthier than they think, or that one can incur a shortage of hospital beds.

Second, but more grave, is the policymaking. No 10 appears to be enamoured with “scientism” – things that have the cosmetic attributes of science but without its rigour. This manifests itself in the nudge group that engages in experimenting with UK citizens or applying methods from behavioural economics that fail to work outside the university – yet patronise citizens as an insult to their ancestral wisdom and risk-perception apparatus. Social science is in a “replication crisis”, where less than half the results replicate (under exact same conditions), less than a tenth can be taken seriously, and less than a hundredth translate into the real world.

So what is called “evidence-based” methods have a dire track record and are pretty much evidence-free. This scientism also manifests itself in Boris Johnson’s chief adviser Dominic Cummings’s love of complexity and complex systems (our speciality) which he appears to apply incorrectly. And letting a segment of the population die for the sake of the economy is a false dichotomy – aside from the moral repugnance of the idea.

As we said, when one deals with deep uncertainty, both governance and precaution require us to hedge for the worst. While risk-taking is a business that is left to individuals, collective safety and systemic risk are the business of the state. Failing that mandate of prudence by gambling with the lives of citizens is a professional wrongdoing that extends beyond academic mistake; it is a violation of the ethics of governing.

The obvious policy left now is a lockdown, with overactive testing and contact tracing: follow the evidence from China and South Korea rather than thousands of error-prone computer codes. So we have wasted weeks, and ones that matter with a multiplicative threat.

• Nassim Nicholas Taleb is distinguished professor of risk engineering at New York University’s Tandon School of Engineering and author of The Black Swan. Yaneer Bar-Yam is president of the New England Complex System Institute

https://www.theguardian.com/commentisfree/2020/mar/25/uk-coronavirus-policy-scientific-dominic-cummings?CMP=share_btn_tw

 

Edited March 26, 2020 by vememah

[Luther]

Dobar tekst Taleba

[vememah]

Evo malo ohrabrujućih vesti: 

Šef tima Imperijal koledža Nil Ferguson danas izjavio da uz primenu sadašnjih mera društvenog udaljavanja i pojačano testiranje očekuje ispod 20.000 žrtava u Britaniji, pik za dve-tri nedelje i to da će generalno gledano kapaciteti bolnica biti dovoljni osim na pojedinačnim mestima.

UK has enough intensive care units for coronavirus, expert predicts

HEALTH 25 March 2020

By David Adam

The UK should now be able to cope with the spread of the covid-19 virus, according to one of the epidemiologists advising the government.

Neil Ferguson at Imperial College London gave evidence today to the UK’s parliamentary select committee on science and technology as part of an inquiry into the nation’s response to the coronavirus outbreak.

He said that expected increases in National Health Service capacity and ongoing restrictions to people’s movements make him “reasonably confident” the health service can cope when the predicted peak of the epidemic arrives in two or three weeks. UK deaths from the disease are now unlikely to exceed 20,000, he said, and could be much lower.

The need for intensive care beds will get very close to capacity in some areas, but won’t be breached at a national level, said Ferguson. The projections are based on computer simulations of the virus spreading, which take into account the properties of the virus, the reduced transmission between people asked to stay at home and the capacity of hospitals, particularly intensive care units.

The Imperial model has played a key role in informing the UK’s coronavirus strategy, but this approach has been criticised by some. “To be fair, the Imperial people are the some of the best infectious disease modellers on the planet,” Paul Hunter at the University of East Anglia, UK, told New Scientist last week. “But it is risky to put all your eggs in a single basket.”

Ferguson said the current strategy was intended to keep transmission of the virus at low levels until a vaccine was available. Experts say that could take 12 to 18 months and Ferguson acknowledged it was impractical to keep the UK in lockdown for so long, especially because of the impact on the economy. “We’ll be paying for this year for decades to come,” he said.

The UK government is aiming to relax restrictions on people’s movements only when the country has the ability to test more people for the virus, said Ferguson. Some have criticised the UK for not following the advice of the World Health Organization to “test, test, test”. But Ferguson said community testing and contact tracing wasn’t included as a possible strategy in the original modelling because not enough tests were available.

He said the UK should have the testing capacity “within a few weeks” to copy what South Korea has done and aggressively test and trace the general population.

New data from the rest of Europe suggests that the outbreak is running faster than expected, said Ferguson. As a result, epidemiologists have revised their estimate of the reproduction number (R0) of the virus. This measure of how many other people a carrier usually infects is now believed to be just over three, he said, up from 2.5. “That adds more evidence to support the more intensive social distancing measures,” he said.

His comments come as a team at the University of Oxford released provisional findings of a different model that they say shows that up to half the UK population could already have been infected. The model is based on different assumptions to those of Ferguson and others involved in advising the UK government.

Most importantly, it assumes that most people who contract the virus don’t show symptoms and that very few need to go to hospital. “I don’t think that’s consistent with the observed data,” Ferguson told the committee.

https://www.newscientist.com/article/2238578-uk-has-enough-intensive-care-units-for-coronavirus-expert-predicts/

Video snimak nastupa:
https://parliamentlive.tv/Event/Index/2b1c71d4-bdf4-44f1-98fe-1563e67060ee

[Lord Protector]

 

TED LEWIS CENTER FOR HOMELAND DEFENSE AND SECURITY DEPT. OF NATIONAL SECURITY AFFAIRS

NAVAL POSTGRADUATE SCHOOL

Levy Flights and Walks
BY TED LEWIS · PUBLISHED SEPTEMBER 21, 2011 · UPDATED JUNE 13, 2018

 

Lecture/presentation.
Ted Lewis.

Levy flights and walks are paths taken by animals and humans that qualify for the Casinos of Extremistan because they obey power laws. Professor Ted Lewis uses the spread of SARS and terrorism to illustrate Levy flights and walks, and show that epidemics and terrorism obey power laws just like any other normal accident of Extremistan. In this lecture, Dr. Lewis makes several surprising claims. For example, he suggests that terrorism is destined to die out, because of the shape of its power law.

 

 

Edited March 26, 2020 by slow

[vememah]

 

 

[vememah]

Izašla je analiza koju je uradio IHME (Institute for Health Metrics and Evaluation) za SAD, procenjuju da će tamo biti oko 80.000 mrtvih i da će pik biti 14. aprila, ali samo pod uslovom da sve savezne države veoma brzo uvedu i strogo sprovode mere društvenog udaljavanja i ne ukidaju ih do kraja epidemije.

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Forecasting COVID-19 impact on hospital bed-days, ICU-days, ventilator days and deaths by US state in the next 4 months

RESULTS

Compared to licensed capacity and average annual occupancy rates, excess demand from COVID-19 at the peak of the pandemic in the second week of April is predicted to be 64,175 (95% UI 7,977 to 251,059) total beds and 17,309 (95% UI 2,432 to 57,584) ICU beds. At the peak of the pandemic, ventilator use is predicted to be 19,481 (95% UI 9,767 to 39,674). The date of peak excess demand by state varies from the second week of April through May. We estimate that there will a total of 81,114 deaths (95% UI 38,242 to 162,106) from COVID-19 over the next 4 months in the US. Deaths from COVID-19 are estimated to drop below 10 deaths per day between May 31 and June 6.

CONCLUSIONS AND RELEVANCE

In addition to a large number of deaths from COVID-19, the epidemic in the US will place a load well beyond the current capacity of hospitals to manage, especially for ICU care. These estimates can help inform the development and implementation of strategies to mitigate this gap, including reducing non-COVID-19 demand for services and temporarily increasing system capacity. These are urgently needed given that peak volumes are estimated to be only three weeks away. The estimated excess demand on hospital systems is predicated on the enactment of social distancing measures in all states that have not done so already within the next week and maintenance of these measures throughout the epidemic, emphasizing the importance of implementing, enforcing, and maintaining these measures to mitigate hospital system overload and prevent deaths.

http://www.healthdata.org/research-article/forecasting-covid-19-impact-hospital-bed-days-icu-days-ventilator-days-and-deaths

 

Studija:
http://www.healthdata.org/sites/default/files/files/research_articles/2020/covid_paper_MEDRXIV-2020-043752v1-Murray.pdf

Dodatak:
http://www.healthdata.org/sites/default/files/files/research_articles/2020/CovidModel Appendix.pdf

https://covid19.healthdata.org/projections

(iz studije)

Edited March 27, 2020 by vememah

[vememah]

Nova procena Imperijal koledža, ovaj put za ceo svet: u optimističkom scenariju da sve zemlje blagovremeno sprovedu društveno udaljavanje i održe ga tokom cele epidemije, procenjuju da će širom sveta biti 1,8 miliona mrtvih. Ako malo zakasne, biće 10 miliona mrtvih, a ako puste virus da se nesmetano širi - 40.

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Pandemic deaths could top 1.8 mn even with tough response: study

 

The death toll from the coronavirus pandemic sweeping the globe could hit 1.8 million worldwide this year even with swift and stringent measures to stop it, according to a study from Britain's Imperial College published Thursday.

Researchers estimate that tens of millions of lives could be saved if governments act fast to adopt strict public health measures, including testing, quarantining and broad social distancing.

The latest report from Imperial College London, whose previous research spurred the British government to ramp up its efforts to curb the virus, comes as an AFP toll based on country data and World Health Organisation figures showed global infections topping 500,000, including more than 22,000 deaths.

The Imperial College modelling simulations are based on current data about the severity of the virus -- its contagiousness and estimated mortality rate -- as well as demographic and societal factors.

In a sobering projection of what could have happened with no interventions at all, the study said that if left unchecked COVID-19 could have infected almost everyone on the planet this year and killed 40 million people.

The report then looks at different levels of response, from spontaneous social distancing to the tough lock down measures currently imposed in some worst-affected countries, and projects the potential health impacts across 202 countries.

With strict containment measures imposed early enough -- resulting in a at the rate of deaths of 0.2 per 100,000 of population per week -- the modelling shows a death toll of 1.86 million people, with nearly 470 million infected this year.

If the same measures were taken later -- leading to at 1.6 deaths per 100,000 of population per week -- the estimated toll rises sharply to 10.45 million deaths and 2.4 billion people infected.

"Our analysis highlights the challenging decisions faced by all governments in the coming weeks and months, but demonstrates the extent to which rapid, decisive and collective action now could save millions of lives," the authors said.

Estimates of mortality levels and healthcare demand were based on data from China and high-income countries, the report said, adding that variances in health systems could result in different patterns in low income countries.

They stressed that the modelling mapped out "possible trajectories" for the pandemic and containment strategies, based on countries that have been affected early in the pandemic.

"However, at the current time, it is not possible to predict with any certainty the exact number of cases for any given country or the precise mortality and disease burden that will result."

The report does not take into account the social and economic costs of the containment measures, "which will be high and may be disproportionately so in lower income settings".

It also warned that "suppression strategies will need to be maintained in some manner until vaccines or effective treatments become available to avoid the risk of later epidemics".

 

https://www.france24.com/en/20200326-pandemic-deaths-could-top-1-8-mn-even-with-tough-response-study

 

Studija:
https://www.imperial.ac.uk/media/imperial-college/medicine/sph/ide/gida-fellowships/Imperial-College-COVID19-Global-Impact-26-03-2020.pdf

Edited March 27, 2020 by vememah

[iDemo]

15 hours ago, vememah said:

Social science is in a “replication crisis”, where less than half the results replicate (under exact same conditions), less than a tenth can be taken seriously, and less than a hundredth translate into the real world.

#jeza

[iDemo]

22 hours ago, slow said:

Da, i najverovatnije je u pravu...

Vrlo vrlo verovatno.

[vememah]

Fight against Covid-19

Confidential government study describes corona scenarios for Germany

According to SPIEGEL information for the Ministry of the Interior, several scientists have investigated how the epidemic could spread. In a worst-case scenario, they describe what happens if the state does too little against Corona.

By Martin Knobbe
27.03.2020, 08:18

In a study, the Federal Ministry of the Interior has developed scenarios for the spread of the coronavirus. The study, which is classified as confidential, entitled "How we get Covid-19 under control", involved scientists from different disciplines. They were asked to answer the question as to when a health crisis might turn into a state and systemic crisis - and how this could be prevented.

The study, which is available to SPIEGEL, was also presented to the Ministry of Defence and the Federal Chancellery on 22nd March. The "Süddeutsche Zeitung" also reported on it.

In a worst-case scenario, the scientists describe what will happen if the state does little to combat the corona epidemic, for example, only bans major events and restricts travel. As a result, 70 percent of the population would soon be infected, more than 80 percent of intensive care patients would have to be turned away from hospitals, and the death toll in Germany would exceed the million mark.

Another scenario describes the strict suppression of new infections, including extensive testing and strict isolation of those infected. To achieve this, test capacities would have to be increased over the next few weeks and mobile test stations would have to be set up. The study initially assumes an increase in test capacities to 100,000 per day, and a few weeks later to 200,000 per day. According to the Federal Ministry of Health, 200,000 tests per week are currently carried out in Germany.

"In order to make testing faster and more efficient", the paper of the Ministry of the Interior states, "the use of Big Data and Location Tracking is inevitable in the long term". If this model is followed, the scientists calculate that around one million people in Germany would be infected, but only 12,000 would die. The strict procedure would have to be maintained for two months. However, since only a small part of the population would be immunized against the virus after that, "continued high vigilance would have to be maintained," they say.

Federal Minister of the Interior Horst Seehofer (CSU) told SPIEGEL that he had also oriented himself on a study by London's Imperial College on intervention measures against corona. This study shows ways to deal with pandemics. Suppression" is an attempt to prevent the further spread of the virus with strict measures. Mitigation" refers to containment, i.e. the attempt to allow the number of cases to rise more slowly so that the health system has enough time to prepare.

"I am a firm supporter of suppression, even if this method is much more expensive," said Seehofer. "But it saves the most lives."

https://www.spiegel.de/politik/deutschland/corona-in-deutschland-vertrauliche-regierungsstudie-beschreibt-verschiedene-szenarien-a-1cafaac1-3932-434d-b4de-2f63bce0315d (translated by Deepl)

[Lord Protector]

Everything’s Canceled

While all the countries on this tracker are united behind a common goal – stamping out COVID-19 as soon as possible – each country has its own approach and unique challenges when it comes to keeping their population safe. Of course, countries that are just beginning to experience exponential growth in case numbers have the benefit of learning from mistakes made elsewhere, and adopting ideas that are proving successful at slowing the rate of infection.

Many jurisdictions are implementing some or all of these measures to help flatten the curve:

• Quarantining
• Encouraging social distancing
• Encouraging working from home
• Closing schools and other institutions
• Placing hard limits on the size of crowds at events

The following chart explains why this last measure is critical to limiting the spread of the virus.

In scenario B above, which assumes just 20,000 active cases of COVID-19 in the U.S., there’s nearly a 50% chance an infected person will be attending a 10,000 person conference or sporting event. This is precisely the reason why temporary limits on crowd size are popping up in many jurisdictions around the world.

 

 

https://www.visualcapitalist.com/infection-trajectory-flattening-the-covid19-curve/

Edited March 28, 2020 by slow

[iDemo]

Ovo je vishe vizuelizacija™ nego modeliranje al' svakako vredi... 

Pogledati i 'notes' ispod klipa. 

 

[Lord Protector]

 

[Lord Protector]