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Messages - epsilon

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actual epidemic charts / Re: case numbers
« on: February 14, 2020, 06:43:20 pm »
Deaths and severe cases doubling period roughly 3 days during the early, exponential phase.

I think this gives us a good, rather unbiased proxy of actual epidemic doubling time.

After all, when assessing doubling periods it does not matter if there is systemtic under-counting of cases (i.e. if cases are off by a certain fixed factor) the doubling time will be the same.

Also consistent with latest research.

Former research (Leung et. al) used to rely on case doubling estimates of 7 days.

Many people have difficulty understanding nature of exponential growth.

Case doubling of 3 days, means: epidemic is one thousnad times larger after just 4 weeks and one million times larger after 8 weeks.

nCoV - discussion / Re: estimating the cfr
« on: February 14, 2020, 02:28:23 pm »
My personal estimate (educated guess) is that prevalence of infections already reached up to 1% of the Wuhan population (i.e. 100k of 10M) before they shut the city down.

Also, very recent paper estimated that 900 infected air passengers travelled from Wuhan tp 300+ cities outside china in the 2 weeks before the travel ban.

Yet another study estimated that 3 imported seed cases spark community outbreak with 50% probability.

So if those studies are not too far off, it seems pandemic is inevitable.

Concerning cfr I still think it could be "only" 0.5% BUT only with fully functional health system. Otherwise 5%, 15% ?
In one study, 15% need at least additional oxygen, 5% ICU.

Health system collapse is, IMO, the most worrysome risk with COVID19 because the shortage of hospital cpacity and protective equipment (and the new studies showing very high infection risk for doctors and nurses could lead not only to large number massive fear-based non-compliance of HC workers)

nCoV - discussion / Re: Scenarios for the coming months
« on: February 13, 2020, 12:34:26 pm »
Sorry, I did not clearly express myself.
What I wanted to say is not that the virus itself necessarily mutated to a milder form, but that the early media reporting, case and death counting etc. was very much biased.

The reason for this was that, most probably, that they completely overlooked the mass of many very mild/asymptomatic cases.
In the end it came apparent that mild infections were not only 10x under reported, but more than 100x.

I still hope that this is playing out similarly with COVID19.

What if virus prevalence in Wuhan is not 1% but already 10% of population with most of them only a little headache and runny nose ?

This would also explain the slowing of the spread in Wuhan due to increasing herd immunity.

nCoV - discussion / Re: estimating the cfr
« on: February 13, 2020, 12:25:44 pm »
apparantly in no city, in no country except maybe Wuhan it did take off yet.

Yes. That's a very interesting observation that I cannot explain at the moment.

Given the extremely explosive epidemiologic parameters (latest research: R0>4, doubling each 2.4 days!) we should be really seeing signs of large scale outbreaks some where else by now.  It's impossible that they perfectly identified an isolated all exported cases everywhere.

But all we see is small to mid sized, controlled clusters of 50-100 cases in Singapor and on the cruise ship.

Maybe its just too early.
Remember in Wuhan it was silently circulating from end of November until end of December when the first signs of pneumonia clusters revealed themselves.

The next 2-4 weeks are key !

nCoV - discussion / Re: Tracking coronavirus: Map, data and timeline
« on: February 13, 2020, 12:15:56 pm »
So we now know that deaths have actually been under counted by about factor 2 (now about 200+ daily increase vs. 100+ yesterday)

But infections probably even (much) more  under counted than deaths.

So final CFR may turn out quite low.  (my estimate: less than 1% BUT only in non-overwhelmed health system)

news / Re: Hubei press conferences
« on: February 13, 2020, 12:08:35 pm »
thanks for this. Really interesting 1st-hand info i've not seen elsewhere yet.

actual epidemic charts / Re: hubei vs. rest of China
« on: February 13, 2020, 12:05:13 pm »
money is always a problem , but you said "cheap"

It could be worth it in some countries.

The problem is people are infective before having symptoms and maybe
also before symptoms can be detected.

I think it must be made illegal to infect others carelessly or to not report
a risk-level and isolate/protect if required.
See China.

nCoV - discussion / Re: estimating the cfr
« on: February 11, 2020, 05:28:22 pm »
the numbers of new confirmed cases Hubei ex Wuhan and China ex Hubei
do really go down.

This is a good sign that control or even containmant works for prepared cities. They had a head sart of 2 weeks on Wuhan.
And they really implemented drastic measures (e.g. school closures) right from the start even when they had mainly imported cases fro Wuhan.

We should probably do the same now in our on cities/countries. But I'm afraid we are only managing this RE-actively instead of PRO-actively.

What I still not understand is why new infections in Wuhan do not decrease drastically. They live in maximum isolation for 3 weeks now. How could they continue infectiong each other. Airborne transmission ?

See also this very recent paper :

reproductive number R_c, i.e. the transmissibility of the virus AFTER isolation/quarantine measuers in China still larger than 1. (Epidemics can only be stopped if R_c < 1.)
My take: Even the draconic chinese isolation measures not yet sufficient.

nCoV - discussion / Re: estimating the cfr
« on: February 11, 2020, 07:06:04 am »
I generally avoid drawing conclusions from official china numbers from Wuhan/Hubei (I have some more trust in the chinese numbers outside Hubei). This is not to say, the official lie intentionally, rather I think it is simply a problem of capacity and chaos in an near-overwhelmed health system)

Fortunately there are many studies now, that model the spread and severity of the epidemic using only non-china data and air travel models.

The other point we all should keep in mind is that you cannot simply mix numbers from before Jan 23 (i.e. before the drastic isolation measures) with the numbers after the shutdown.

Before the shutdown we probably had real exponential community transmission with case doubling of 3 days. (You can even use the official numbers to see that because for case doubling estimation it does not matter whether the numbers are off by a factor of ten)

Now, after the sutdown (plus one incubation period) i.e. roughly after February 1, we see about linear growth which means that the isolation measures work in so far as exponential spread is stopped (R_effective <= 1)
Unfortunately there is still no sign that the isolation measures are enough to not only slow down but actually END the epidemic (R_effective << 1)

This is crucial, because isolation cannot be maintained forever.


studies,summaries / Re: spread modeling
« on: February 10, 2020, 01:56:48 pm »
New study puts case doubling rate at 2.9 days (half than previous estimates !)

the early outbreak of 2019-nCoV could have been spreading much faster in Wuhan than previous estimates.

This is very concerning (but is consistent with R0=3 and the recently published very short incubation period of 3 days).

This means not only does the epidemic spread twice as fast as presumed, but it means that spread is exponentially twice as fast.

Example: increase in number of cases after 4 weeks:

previous estimate (case doubling 7 days) :   16 fold increase  (2^4)
New estimate (doubling every 3 days) :  1.000 fold increase (2^10)

This explosive growth perfectly explains why Wuhan got overwhelmed so quickly.

If we continue to understimate this virus in our countries outside China we are prone to the same playbook.

actual epidemic charts / Re: hubei vs. rest of China
« on: February 10, 2020, 09:19:36 am »
did they well because they were better preparing or just because they were
not being overwhelmed ?

They were not overwhelmed because they were prepared.

It was wise to immediately close schools, workplaces, public transport etc. even at a time when they had only imported cases from Wuhan.

Its my concern that gouvernments outside of china are now in the same position resp. "import from china" than the other chinese Provinces were with respect to "import from Wuhan."
We must not miss this window of opportunity. But here in Germany, for example, the only thing they do is distributing flyers at the airports  >:(

nCoV - discussion / Re: estimating the cfr
« on: February 10, 2020, 08:52:27 am »
"Obviously many cases were unconfirmed, especially in Wuhan. There were those 5M people
leaving the city at that time.It is likely that severe cases had a greater probability
of being confirmed."

Th big question is: How prevalent was the virus already in the general community when Wuhan Quarantaine begun ?
My gut feeling is at least 1% prevalence, maybe even 10% obviously (and hopefully) this would imply many more mild cases than assumed previously.
Most models based on exported cases put the pre-shutdown absolut case numbers between 25k and 150k, corresponding to roughly 100k/10M = 1% prevalence.
So there is, unfortunately, still large uncertainty of one order of magnitude (factor 10) about the actual pathogenity/severity of this virus.

What we really need are seroprevalence studies for 2019nCoV antibodies in every large community.

My hope is, that sero prevalence is very high already because this means that the vast majority of cases are mild or asymptomatic cases.
But until we have the data, this may be just wishful thinking.

nCoV - discussion / Re: Scenarios for the coming months
« on: February 10, 2020, 07:55:23 am »
why do you think it's likely mild

I have to admit it is partly due to wishful thinking. But the other reason is my experience with how the 2009 H1N1 swine flu pandemics played out.

I vividly remember the reports from Mexico at the time with CFR estimates of 10% then 1-5%the media full with comparions to 1918 spanish flu,  and the reports of healthy young patients all over the world on ventilators with severe pneumonia.

As the pandemic unfolded, two things became more and more clear: 1. it was hopeless to try to contain it and 2. somehow the proportion of very mild cases  increased dramatically until in the end it was even less serious than the seasonal flu.

nCoV - discussion / Scenarios for the coming months
« on: February 09, 2020, 06:33:33 pm »
I see three major possible scenarios for the future development of 2019nCoV:

    A) It will eventually be contained like SARS in 2003 (though only after about 10 times larger outbreak magnitude)

    B) It will go fully pandemic like 2009 H1N1 (>50% global attack rate) and very low cfr (<0.1%) due to many mild cases.

    C) Will go fully Pandemic but with relatively high 1-2% cfr i.e. more like 1918 spanish flu.

Personally I would put the following probabilities : A=>20%, B=>60%, C=>20%

What do you think ?


Transmission through the eye has been established fact for other respiratory viruses:

"Viral infection of the lungs through the eye."

"These results establish the eye as a major gateway of respiratory infection and a respiratory virus as a bona fide eye pathogen"

So its not surprising that goggles are recommended as PPE when dealing with viruses like SARS/MERS/2019nCoV

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