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Corona Simulator (washingtonpost.com)
271 points by mef 15 days ago | hide | past | web | favorite | 79 comments



> “As Lawrence O. Gostin, a professor of global health law at Georgetown University, put it: “The truth is those kinds of lockdowns are very rare and never effective.””

uh, except... the one we all just watched be successfully implemented in wuhan?


Except what was really implemented in Wuhan was really not just quarantine, but was also an extreme form of social distancing, where essentially the whole province of Wuhan was locked down.


*Hubei


We'll need to wait 10 days to see if it was effective in Italy too, but other countries should start implementing it ASAP.

Lot of EU countries / USA are already late with respect to our timeline, aka they may have it worst if they don't act fast.


China did not prevent Covid-19 from spreading.

They simply did not test for Covid-19 in other states. US repeated the same strategy: no testing for Covid-19 - means no information about Covid-19 cases.


>uh, except... the one we all just watched be successfully implemented in Wuhan?

China have successfully paused the epidemic, but they haven't stopped it. Unless we fully eradicate the disease globally (highly unlikely given the presence of asymptomatic carriers and the spread of the disease to low-income countries), they'll be back to the beginning of the exponential curve as soon as the lockdown is lifted. That's better than nothing, but it's a million miles from a solution.


It's not about stopping the pandemic altogether - it's about reducing the number of people in critical condition at a given time. Italy it's already at peak capacity in it's ICUs, and only thorough social distancing it's possible to reduce the number of people at risk getting infected and clogging an health system that is already short on ventilators and hospital beds.


59 million people in Hubei province. 67,000 confirmed cases, 3000 deaths.

Lets assume all cases were identified. 59 million did not get the disease. It kills 4%.

A vaccine will take at least 18 months to develop. Can China keep Hubei locked down at the current rate for 18 months? Could we do that in the West?

If the answer is no, what happens when we reduce the social distancing?


The idea is that you have say 1000 ICU spots available. Based on your numbers 4.5% of the cases are deadly, but let’s say 10% are severe-to-deadly and require two weeks of ICU care. So that’s 6,700 people or roughly 94,000 man-days of ICU time. In other words if you slow down the rate of infection enough you could fit that 94k into the 1k of beds over time. But if all of them get sick on day one, you are fucked.

Social distancing is about slowing down the spread, not eradicating the disease. What will eradicate it one way or the other is the immune system or death: once you’ve had it you are unlikely to get reinfected or you will die. To avoid the latter case you need ICU time or eventually a vaccine. Also consider that buying a month of time means an extra month to provide more ICU beds, better testing capacity, better understanding of what is effective prevention, etc.


> In other words if you slow down the rate of infection enough you could fit that 94k into the 1k of beds over time. But if all of them get sick on day one, you are fucked.

Average ICU stay is about 2 weeks, so that's 3.6 years to filter everyone through.


  A vaccine will take at least 18 months to develop. 
You can argue that a vaccine would take 18 months to test and deploy, but candidates already exist and are under trial. Moderna (MA, USA) shipped theirs three weeks ago, for one.


In a police state


except it may not be successful yet

you are just taking for granted the data provided to you by an authoritarian state


You don't need to rely on the data by the Chinese government, for several reasons:

1) Lots of epidemiological papers about the Wuhan epidemic use data from phone carriers (not the government) to track the spread and make predictions, and they were generally pretty good with their forecasts. The numbers reported by the government are consistent with the forecasts from scientists.

2) The numbers reported by China are also consistent with the spread observed _outside_ of China. You can't lie about the numbers because every other country would detect an anomalous number of imported cases. (Case point - In Canada, we're importing way more cases from the US than you'd expect if there were actually only 1200 cases in the US. This is rather because the US is lagging so far behind in testing, rather than outright deception.)

The absolute numbers don't even matter that much - what matters is the trend and the number of new cases going to zero. Look at epidemiology paper - they always assume only like 10% of infected cases are tested and confirmed. The epidemic really is coming to a close in China, still gaining momentum in Europe, and coming in a big way soon to North America.


> Lots of epidemiological papers about the Wuhan epidemic use data from phone carriers (not the government) to track the spread and make predictions, and they were generally pretty good with their forecasts. The numbers reported by the government are consistent with the forecasts from scientists.

Please provide a source for this. I have not seen any of this data used. The data I see used is from the CCP's official data.

> You can't lie about the numbers because every other country would detect an anomalous number of imported cases.

This is absolutely false. Because flights have been suspended from China to most countries, and China itself has been on lockdown, the number of imported cases to other countries does not reflect the growth of the virus inside of China.

> The absolute numbers don't even matter that much - what matters is the trend and the number of new cases going to zero. Look at epidemiology paper - they always assume only like 10% of infected cases are tested and confirmed. The epidemic really is coming to a close in China

Please provide proof that is not coming from CCP.

No offense, but there's no reason to believe you on this without providing sources. Most of what you have said smells like BS.


I think the point is that you have to wait until the city gets back to normal to judge the efficacy of the lockdown.


It's uncanny, because the various testing regimes implemented in the places where there have been outbreaks ought to be providing wildly inconsistent data, but the data from around the world is all showing a strikingly similar pattern. Once there's a community outbreak, the starting gun is off and it plays out like clockwork. The best you can hope to do is gum up that clockwork with draconian quarantine measures, because the starting gun is off all over the continental United States. Wash hands across America.


Might wanna read the news.


One thing about this sim bothers me. Having points bounce off each other means they migrate more slowly and increases the effective contact graph diameter. Bouncing points aren't meaningful for the system being modeled. Me staying at home doesn't restrict your movements: our decisions are independent.

IMHO he should turn off the collision model. The effect will still be there, but the logistic parameters will be different.


Yeah this is good for cells in a blood stream, not humans. Also humans interact with other humans unevenly: you see your family and coworkers more often and for more time than a random barista. Except the barista where you always get your coffee on your lunch break. And then you have social mavens who interact with loads of people. If you work in an office with 15 other people, your social circle is likely on the order of like 100-200 people. If you do public speaking for a living, your social circle is in the thousands. Would be better to simulate it that way.

What I don’t get is that we keep hearing quarantine isn’t effective, yet it seems to be in China and South Korea: https://www.businessinsider.com/coronavirus-lockdowns-work-s...


Chinese lockdowns are the most extreme form of social distancing -- everyone in Wuhan and similar hotspots stays home, not just ones for which there's some reason to suspect infection. In South Korea and elsewhere in China, there's special attention to quarantining people who are starting to show symptoms, and close contacts -- but there's also substantial social distancing as well (closures of schools, museums, retail...). There are examples where quarantines have been part of a successful strategy, but it's hard to find one where they've worked with no other elements.


I think it's more of, quarantine isn't economically feasible. But then, things that aren't feasible can often become feasible in different circumstances.


Economically it doesn't make much difference. You can either isolate people now or later. The period of isolation will be roughly the same because you have to wait for the virus to exhaust its pool of hosts (in a household). Definitely politically it makes a big difference.


Now and later make a HUGE difference economically. Time value of money. Business cash flow. Not to mention, if it turns out to be unnecessary later, later becomes never.


The scale of the problem will be so much larger because we aren’t doing a quarantine. In an exponentially growing virus, one single day makes a large difference.


True, there might also be a vaccine in the future.

Another argument is that we just need it to grow slow enough for a vaccine to be ready.


Who is saying quarantine isn't effective?


This article, to start, for multiple paragraphs:

As Lawrence O. Gostin, a professor of global health law at Georgetown University, put it: “The truth is those kinds of lockdowns are very rare and never effective.”


It's a language problem. Things like self quarantine of infected (and potentially infected) people have a big impact on how fast a disease spreads (meeting the bar for "effective" in my mind).

What they don't do is completely stop it.


New cases in China and South Korea have slowed to a crawl.


There were zero cases in Italy 6 weeks ago.

Lets assume China and South Korea manage to stop every single person from having it - even people with mild symptoms, and get 99% of people crossing the borders into quarantine for 14 days.

They then lift the lockdown.

Aren't they simply back to the stage Italy was in 6 weeks ago? A couple of weeks later one or two of the 1% of people avoiding quarantine. They can try the "contain" phase again, but eventually that will fail, so after 4 months from loosening the reigns, they're back into major outbreaks and back with lockdown. Expect that to happen many times over the next 18 months.

Even with a vaccine we haven't managed to eliminate polio or measles, and almost everyone is immune to them and doesn't carry it, we won't be able to eliminate covid either.


It'll be (at a minimum) months with no new outbreaks in an area before social behavior starts to return to what it was before an outbreak. New outbreaks won't look the same as the first ones.

I think it is still early to say we know, but it also looks like there is a period of immunity after infection. So there's a fair chance that will also slow the spread of each repeated outbreak.


Only if a measurable number of people have that immunity. Assuming having it gives you immunity, Hubei has 1 in 10,000 with immunity, that's not enough to change it's spread


“ Polio does still exist, although polio cases have decreased by over 99% since 1988, from an estimated more than 350 000 cases to 22 reported cases in 2017. This reduction is the result of the global effort to eradicate the disease. Today, only 3 countries in the world have never stopped transmission of polio (Pakistan, Afghanistan and Nigeria).” -WHO

You can make a very large dent. My guess is in these 3 countries you’re not seeing every child vaccinated with Polio. Hopefully with COVID-19 the anti-vaxers will quiet down and we’ll get more herd immunity generally.

We don’t know what measures China will take to ensure their curve stays flat. They might keep the lockdown until there are 0 cases and fully close their borders. This is where having a competent authoritarian government that people trust is actually beneficial. They might be able to do it.

Meanwhile I have zero faith that the US gov (where I live) will be able to handle this situation. It’s going to be wide spread, and will leave a giant unemployed workforce in its wake.


The thing is, with these models. Everyone will eventually catch the virus and either dies off or recovers. If this happens in real life, the consequences are dire and catastrophic.

Social distancing and avoiding large groups will obviously save lives and we flatten the curve to allow for treatment of individuals that will require hospitalization. But once the novelty of social distancing wears off. Will the number of cases where people get affected explode once again?

The question is when will this virus go away? (if ever). Will everybody catch it eventually? Will the panic fade and Corona be just another (and much deadlier) strain of the flu?


That’s actually not correct, and the point of the simulations is to show that. By social distancing, you reduce the likelihood of everyone getting the disease. The use of social distancing brings the probability that everyone gets infected at some point closer to 0.0 but doesn’t make it 0.0. It’s possible to have a result where you either have people who were never infected, or ones who are fully recovered.

That’s what they’re driving at.


The major error with the model used in the article is that, in real life, all the points will eventually start to move again.


A key notion is that the maximum capacity of the health care system is limited. Yes everyone will get sick, but we want to keep the total sick at any one time within healthcare limits.

https://www.old.reddit.com/r/coolguides/comments/fglwbc/cool...


That's not true, look at the light blue area in the distancing models.


To be fair, the # of infected never died off completely (the simulation didn't run long enough)


It is still hard to grasp that the entire human civilization will be infected with this not yet fully understood virus.

What if it makes everyone infertile? Real Children of Men scenario.

The measures taken are optimistic, but when everything is one the line, you have to make pessimistic decisions. First avoid human extinction.

Making bets with human kind as the wager are immoral in the highest order.


What if it gives the survivors the strength to resist or fight back something else? If we think about it, human (and not human) very ancient history must be full of these interactions, and our evolution is a consequence also of this kind of thing. Only recently we know how to "protect" ourselves. But if we are in the what-if domain... what if letting it go make us a biologically better being? What if it by chance will give us the protection against some kind of tumor? What if its overall effect, not counting the deaths, is positive and not negative like making us infertile? What if.... We can't know. But we'll see one side of the coin when we'll have defeated this threat. (Which is not an existential threat, anyway, i.e. it won't make us go extinct)


Influenza A started as the Spanish Flu. It likely won't go away - instead either vaccination will control it to much smaller levels, but more likely a less virulent form will evolve and join the other 4 common coronaviruses as another endemic virus.


> The question is when will this virus go away? (if ever).

Probably never. It seems fairly likely there’ll be a vaccine in the next couple of years.


> just another strain of the flu

That's like saying humans are just another type of salmon.


"Another kind of snake", you mean!


Nice simulations. But I believe that using a population of only 200 individuals might be giving misleading results because it enters too fast the logistic limit part of the curve before you can experience the early exponential part. https://www.dummies.com/education/science/environmental-scie...


Yep. Would be nice if they let the user play around with the parameters. Might not be feasible to animate thousands of objects in a browser though.


Exactly. The most, at best, could be 1,000, but will that be enough? This project was likely built on a tight deadline and getting it out quickly onto multiple devices was the goal.

If someone has a better approach, I’d love to hear it.


The comparison between social distancing and quarantine has 0 sense. In Italy, we tried distancing, but without strict measures, people won't listen and the virus kept spreading. You can't enforce something like that without police action


We’re there in Seattle right now exact same failure mode


Yeah, I think you need large numbers of tests, because unless you test people positive they are not likely to respect self isolation.


There seems to be a very well defined separation between those who have a relatively high chance of becoming critically ill, and those who have a very low chance. Depending on what you are optimizing for it could be more important to keep those groups separated.

I wonder if having known that for weeks now has lead to better social distancing between those groups, even if interactions within the low risk group has stayed rather high. Could lead to a lot of spread with very little detection because we largely only test for and catch the really bad cases.


My understanding of a lot of countries approaches is that they're not trying to minimise the total number of people that have or will be infected, but they're trying to minimise the maximum number of people infected at a time (to ensure that healthcare is still available to everybody that needs it). In these simulations, that would correspond to drawing some horizontal line across the chart and trying to keep the orange under there the whole time.

I'm not sure if the long-term outlook is "we're all going to get it" like the flu, or we're trying to stave as much of it off before a vaccine is widely available.


> trying to minimise the maximum number of people infected at a time (to ensure that healthcare is still available to everybody that needs it).

It is so, at least in Italy. Basically they told us the reason of these measure is to spread the cases over a larger time frame... but nobody has said it's to reduce the number of cases.


A vaccine may never be available. There are plenty of viruses for which we have been unable to develop an effective vaccine that doesn't kill more people than it saves.


Can I just comment on the (IMO bad) choice of colors? It's hard to see the difference of sick and recovered, especially in the big square.

Other than that, nice simulations. :)


Indeed, the contrast is low and probably not very accessible. Their design system should consider that so it’s not up to some designer or developer to decide case by case during crunch time.


Especially for the color-blind; specifically, those with tritanopia would find it difficult to distinguish the violet recovered balls from the brown sick balls.


>"Recovered person can neither transmit simulitis to a healthy person nor become sick again after coming in contact with a sick person."

The assumption is wrong. There are several cases of recovered patients getting coronavirus again. This virus is similar to HIV. https://www.channelnewsasia.com/news/asia/japan-woman-covid-...


From the reports I've seen, they have tested positive again which is different than getting it again.


Can you find a more credible source.

There will always be individual examples. But what is the norm.


I think this pandemic will reveal many facets on the effectiveness of quarantines/lock downs.

These measures always have a political meaning, because they effectively create a separation between those included and those excluded from the quarantine. Such a political move will pressure some politicians toward implementing these lockdowns if they are targeted toward foreigners and away from them if implemented toward a domestic subgroup.

It may be easy to ban travel from Europe, but very hard to ban travel from Washington state.


The people who don't understand this stuff, aren't failing to understand it because no one wrote about it. It's because they are not white collar or college graduates and are not likely to read The Washington Post in the first place. My father is the perfect example of this. He's dyslexic and so he struggles to read detailed journalism and gets all of his information from cable TV news like Fox News.


There's really not a 1:1 relationship between "college" and "white collar", and "curiosity".

Plenty of people with their fancy college degree are incurious, and plenty of people that barely made it out of high school are curious.

It's an appealing shorthand, but it's not a great one.


Obviously there's not a 1:1 relationship. And I never made such claim. I am saying that the people who read detailed journalism tend to have a higher reading level, e.g. they work in a job where reading and analysis is a daily part of their work, this would be considered white collar.

Please don't put words in my mouth when I never said there was a 1:1 relationship.


What’s sad is cable news visual teams do not have the resources to do these kinds of awesome visualizations.


Can't view due to cookiewall, is this an article about a simulator somewhere (that someone could link) or is the simulator their own?


It has built in javascript simulators.


Why don’t you support the paper and buy a subscription?


Because it isn't nearly worth $90 to me, I barely ever read any of their articles.

It's also not something I can look at before deciding whether I want to pay for it, not like a product in a shop or something I can order and return (unused) for 14 days. If paying 50 cents for this article was possible, I would have no idea what I'm getting (beyond the title "Corona Simulator") or whether it's worth it, though a one-time 50 cents charge would definitely be more considerable than a recurring and more expensive subscription.


Where do you get your news?

General news? Most things that actually impact my life, people (colleagues, friends, family) will tell me about it; the rest mostly passes me by. Some comes from HN, and when there is a big story I'll sometimes browse to nos.nl, but that's about it.

Tech news I keep up with at Tweakers.net, where I have a subscription. Well, and HN again of course, but a lot of that is personal blogs, show/ask HN posts, and a minority of what I click is research/tech news which then breaks down further into many different outlets.

I also use Reddit but the closest sub I have to news is r/globaltalk, so that's mostly people talking about what's going on near them and not journalists that need to be paid.


The problem we’re seeing is that too many people are moving. Seattle was maybe 25% slower Sunday than normal. That’s not enough, people aren’t respecting social distancing or even the 250 gathering limits. Seattle pd is failing to enforce as well.


This is a great intuitive set of models. It also suggests scenarios where a poorly implemented quarantine could make things worse by intensifying contact and increasing spread between those isolated together, and then releasing everyone while still contagious. It drives home that if people are forcibly kept in close quarters for quarantine, its essential to see the full time period through. If resources might eventually wear thin enough that a quarantine may not be sustainable, it's probably better not to do it at all.


This is what happened in China.

People in Wuhan heard the quarantine was coming and hundreds of thousand fled.

Then, everyone was forced to stay together without access to medical supplies due to the quarantine. That is why the fatality rate was so much higher in Wuhan.

If China hadn’t arrested the whistle blowers, the situation would be a lot different.


I think it illustrates what happened on the 'cruise ship' (i.e. close proximity, clustered) quarantines, but it doesn't very well explain what real, individual quarantine would do.


What was interesting on the cruise ships is how few got it. Of the 3,681 tested, only 696 had it - after a month of close quarters. That's under 20%.

Doesn't that suggest it doesn't spread particularly easily?

All in all, 1% of those that caught it died, and cruise ships skew towards older people.




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