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Member since: Sun Jun 4, 2017, 05:46 PM
Number of posts: 1,660

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One month global COVID-19 case load projection with and without Chinese data

The data for this post is taken from https://www.worldometers.info/coronavirus/ retrieved March 16 at 4:00 pm EST.

This graph doesn't address deaths, just the identified cases from Feb 19 to March 16, with projections out to April 16. The projections are all third-order quadratic fits, and the tightness of the fits is given by the R-squared value for each curve. The dividing line between actual and projected cases is the thick line at today's date.

I had previously been plotting both second- and third-order fits, but the current data is diverging further from the second-order fit, resulting in a steadily dropping accuracy. As a result I don't think the second-order fit is useful any more, at least for this dataset. The third-order fits are remarkably tight.

It's clear from the shape of their green line that China has a handle on their spread. To segregate that effect, I plotted the Chinese data separately, and graphed the world data both with and without the Chinese data included. It's evident that the global spread is now being driven by non-Chinese cases. At the moment the major contributors are Italy, Iran, Spain, S. Korea, Germany, France and the USA.

In one month, if social distancing is not effective, the world could have close to one and a half million cases, with almost all of them (1.4 million) outside China.

As of today, the "Total Case" CFR is 4.2%, and the "Closed Case" CFR is 8.3%, based on the reported data for active cases, recovered cases and deaths from the source listed above. It's still early days, of course, but the fatality ratios based on reported data are still climbing.

We're walking (or running?) deeper into the woods

Posted by The_jackalope | Mon Mar 16, 2020, 04:15 PM (1 replies)

Well, I'm in the grip of dread tonight.

I feel like I just saw the Japanese tsunami 200 meters offshore.

My partner and I are 77 and 69 respectively. She has immune problems, I have asthma and a bum heart. So, we're in isolation. We have enough food and TP for at least a couple of weeks, maybe a couple more if we stretch. We've put strict entry rules in place - mostly for me if I have to go out. I doubt we'll be letting anyone in.

Some of you may know that I've been a long-time doomer. I've been preparing myself psychologically for the end of global industrial civilization for 15 years now. But it still surprised me. I thought it would be climate change that would toll the bell, but I know that major depopulation events are always diseases.

I've been running the numbers and reading epidemiologist reports online tonight, and I'm freaked right the fuck out. This thing is far bigger, way more severe and moving much faster than most people realize, or even could realize. Even than I, with all my practice, could realize. I wouldn't be surprised if, when all is said and done, much will have been said, but we'll all be done.

For example, many of us thought it didn't affect younger people so much. I just saw the demographics of positive cases in China, and 30% of them were 20 to 29 years old. Maybe not symptomatic, but definitely contagious.

My curve plots project over a million cases globally by mid-April, but those are based on diagnosed cases. The word from Harvard and Yale is that for every diagnosed case there are 10 to 50 unknown cases, walking around breathing and touching doorknobs.

To quote Kurtz from Joseph Conrad's "Heart of Darkness", "The horror! The horror!"

Sorry to be a Debbie Downer. I'll make sure to call my aged father in his locked-down retirement home regularly to make up for it.
Posted by The_jackalope | Sun Mar 15, 2020, 03:13 AM (43 replies)

I just realized that this feels like watching the Japanese tsunami come ashore

Right now the thin, innocuous white like on the horizon is about 200 metres offshore, and we're running for high ground. When it hits, it will sweep all before it.

Posted by The_jackalope | Sat Mar 14, 2020, 06:47 PM (6 replies)

Another curve fitting exercise

I just graphed the global COVID-19 case data from https://www.worldometers.info/coronavirus/ from Feb 19 to today in Excel.

I fitted two trendlines to the data, second-order and third-order polynomials, both projected out one month. The fit for the second-order trendline is 0.9909, and the projection indicates half a million cases worldwide in a month. The third-order trendline has a fit of 0.9992, and the projection for April 15 is 1 million cases.

My expectation is that the final number will be between the two - closer to the smaller number if social distancing is relatively successful around the world, but closer to the upper number if it is not.

The CFR for resolved cases (recovered+died) is currently around 7%, but has climbed from 6.3% over the last two or three days. The percentage of recovered cases has dropped from 53% to 49% in the same time, meaning that the spread of active cases is accelerating.

No warrantee express or implied, only one per customer, offer void where prohibited, yadda yadda.
Posted by The_jackalope | Sat Mar 14, 2020, 01:06 PM (11 replies)

A more realistic CFR is in the neighbourhood of 7%, not 1% or even 3.5%

Potential Biases in Estimating Absolute and Relative Case-Fatality Risks during Outbreaks

This section is pertinent to a point I've been trying to get across, with little success so far:

Bias due to delayed reporting.

During an ongoing epidemic, at any week w the persons who have died up to time w will not be the only ones to die of the infection among those who became cases by w. The denominator of the CFR (cases) includes persons who have not yet died of the infection, but will do so in the future. Thus the CFR by w will be less than the true CFR. This bias will be particularly severe for infections that are increasing rapidly in incidence and for which the infection–death time interval is long. (my emphasis)

In the current global situation, these criteria are in play. The infections are increasing rapidly, and the infection-death interval is long relative to the rate of infection.

Today (March 12), there are ~128,000 identified infections, of which ~4700 have died and ~68000 have recovered. So 57% of the identified infections have so far resolved in either recovery or death, while 43% (~55300) are still active, without resolution one way or the other. As time goes on, those 55000 active cases will resolve in either recovery or death.

All else being equal, we can expect that about the same proportion of the active cases will die as have died in the first half of the infections that have already resolved. In other words, of the currently infected cohort we have 4700 known deaths, with a similar number yet to come.

If that holds true, there will ultimately be over 9,000 deaths from the 128,000 currently known infections.

The naive calculation of CFR that everyone is using (but still studiously avoiding in favour of the influenza numbers) uses the identified infection number, for a calculation of 4700/12800 = 3.7%. In fact, the probable eventual CFR for today's situation, by the time all currently identified infections have resolved, will be more like 9000/128000 = ~7%.

The fact that there are undetected cases out there does not change this calculation. Those cases are in the same situation as the currently active but unresolved cases. Those cases will develop into symptomatic illnesses at the same rate as those identified but asymptomatic cases today, and will then either recover or die. Along the way they may contribute to the spread through asymptomatic transmission, but the eventual CFR will, again, be unaffected.

If the average trajectory of the individual illnesses remains the same as it is today, the 7% rate will continue to apply. The only way to change the CFR, as far as I can tell, is to change the outcome of individual illnesses on a large scale. Changing the rate of spread will not affect the CFR.

It's important to remember that this calculation is based on a global average of disease trajectories, and when all is said and done, different countries will exhibit different CFRs.

I'm not an epidemiologist, just a guy on the net. That doesn't necessarily mean I'm wrong.

The world is right to be a freaked out. You don't close down Italy or cancel the NBA season over the flu. A 7% CFR is a whole other kettle of carp.
Posted by The_jackalope | Thu Mar 12, 2020, 11:05 AM (6 replies)

The true death rate at this point is 6.3%

You don't count the active cases. There are 68000 recoveries and 4600 deaths. 4600/72600 = 6.3%

This thing is 30 to 50 times more lethal than the flu.

It's self-quarantine time for everyone.
Posted by The_jackalope | Thu Mar 12, 2020, 12:11 AM (33 replies)

The case fatality rate for COVID-19 is not "about 2%" - it's 3.4%

Based on tonight's numbers from https://www.worldometers.info/coronavirus/ : Deaths 2804, Cases 82,183, the case fatality ratio is 3.41%

Not only that, but the fatality rate has been climbing steadily for the last two weeks:

12-Feb 2.13%
13-Feb 2.15%
14-Feb 2.27%
15-Feb 2.41%
16-Feb 2.49%
17-Feb 2.55%
18-Feb 2.67%
19-Feb 2.81%
20-Feb 2.93%
21-Feb 3.04%
22-Feb 3.13%
23-Feb 3.31%
24-Feb 3.37%
25-Feb 3.41%
26-Feb 3.41%

That climb could just be an artifact of slowing case growth, but maybe not. I'm no pandemiologist , but this behaviour of the data worries me. At the very least, the white coats and empty suits should be using more accurate numbers, in the interests of transparency.
Posted by The_jackalope | Thu Feb 27, 2020, 01:36 AM (43 replies)

The total mass of insects is falling by 2.5% a year

From this year-old article:

"The total mass of insects is falling by a precipitous 2.5% a year, according to the best data available, suggesting they could vanish within a century."

Interestingly, ominously, but perhaps neither surprisingly nor coincidentally, that decrease of 2.5% a year is the same rate that the global GDP is increasing.

I'd gladly trade my leftover insects for cash, wouldn't you?

Plummeting insect numbers 'threaten collapse of nature'

The world’s insects are hurtling down the path to extinction, threatening a “catastrophic collapse of nature’s ecosystems”, according to the first global scientific review.

More than 40% of insect species are declining and a third are endangered, the analysis found. The rate of extinction is eight times faster than that of mammals, birds and reptiles. The total mass of insects is falling by a precipitous 2.5% a year, according to the best data available, suggesting they could vanish within a century.

The planet is at the start of a sixth mass extinction in its history, with huge losses already reported in larger animals that are easier to study. But insects are by far the most varied and abundant animals, outweighing humanity by 17 times. They are “essential” for the proper functioning of all ecosystems, the researchers say, as food for other creatures, pollinators and recyclers of nutrients.

Insect population collapses have recently been reported in Germany and Puerto Rico, but the review strongly indicates the crisis is global. The researchers set out their conclusions in unusually forceful terms for a peer-reviewed scientific paper: “The [insect] trends confirm that the sixth major extinction event is profoundly impacting [on] life forms on our planet.
Posted by The_jackalope | Wed Feb 19, 2020, 04:11 PM (8 replies)

As I watched Rachel lay it out tonight, my blood ran cold.

For 15 years now I've been speculating about the collapse of civilization. I think this will be due to biophysical factors like overpopulation, overconsumption, deforestation, desertification, the loss of fresh water resources, and above all the knock-on effects of climate change, especially the disruption of food supplies brought on by extreme weather events caused by disruptions in the jet stream. I am fully convinced that we are already over the edge and into the avalanche.

One of the consequences that I expected to see as the multi-factorial stresses on societies increased, is the spread of authoritarian governments and the resulting destruction of democracies around the world. My expectations have not been disappointed.

But I never expected to be living just across the border from such a society, watching the process of social collapse unfold in front of my eyes, in real time, on my TV, in the terrified comfort of my living room in Ottawa.

I hope (and if I were religious I would pray) that you will pour out into the streets en masse.

If not you, then who? If not now, then when?
Posted by The_jackalope | Thu Feb 13, 2020, 12:34 AM (18 replies)
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