I've finished The Gospel according to "Frozen II" (or, why Elsa is Jesus) - but I'm still not sure if I'm happy with it. I'm considering revisiting it again in the future, perhaps putting out a condensed version of it.
You may next want to read:
A systematic mythology of the "Frozen" universe
The Gospel according to Disney's "Frozen"
Another post, from the table of contents
Coronavirus endgame: how we get back to normal
(Same disclaimer as before: I'm not a medical or public health professional, listen to them over me if they contradict me in any point in their expertise. I do have this to say for myself, though: my last two articles have played themselves out quite well in the progression of this coronavirus pandemic.)
The current state of things
Mere hours after I published my last article, the San Francisco Bay Area got a "shelter in place" order. Since then many other cities and states have followed up with similar orders. I haven't tracked all such measures, but much of the United States is now in some form of lockdown. I feel like the societal mood has very much changed, to where people are now, finally, taking this seriously.
We are approaching the endgame now. Where do we go from here? And how do we get things back to normal, as quickly as possible? Some people are fantasizing an apocalyptic future, where we stay locked in for months and venture into the virus-infected outside world only to fight over food and toilet paper. Is that what lies ahead? It's clear that our current level of suppression cannot persist indefinitely, but how will it end, and what will life look like when it does?
First, let's go over some good news. Lockdowns are easy to implement, and they work. Once every infected person infects fewer than one additional person on average (R0 < 1), the mathematics of the exponential function now work against the virus, and its numbers collapse with the same rapidity it had during its growth. South Korea and China had already broken the exponential growth long ago, and now, with the latest numbers, it looks like Italy has turned the corner as well, as I said it would.
The major population centers for the U.S (in particular the SF Bay area, where I live) should also reach this point in another week or so. There are other parts of the country where the virus started later, so they will be on a time-delay from the major cities. Again I can't keep track of the different levels of infection all across our vast and diverse country, but in any given area, once your city is in lockdown, the virus will die down in a matter of a few weeks.
What then? If we simply go back to normal, the virus will just flair up again, and we'd be right back to where we started. So does that mean we have to stay locked in indefinitely? That's clearly unsustainable. Fortunately, there's an easy way forward - one that is easy to implement, keeps the number of infections and deaths low, and restores us to mostly "normal life" in just a few weeks.
The way forward - phase 1: lockdown
First, we stay locked down until the worst passes. The healthcare systems are bracing for impact right now, and more infections now will worsen their caseloads and the outcomes for their patients. Stay in your homes, and help out your neighbors and local businesses while maintaining social distancing.
In the meantime, our testing capacity needs to increase massively. Things have certainly improved in testing since the botched initial rollout, but I believe we have much more to do. The rest of this plan hinges on accurately measuring the level of infection in the population, at each local level - every state and every city. We will need enough tests to detect infection levels like 0.01%, everywhere in the country.
In any case, with the lockdown, the numbers will decline. The medical professionals will get slammed for a short time and heroically fight their battles. They will come out victorious on the other side, because the virus will have been starved of new victims. At this point, we can start the next phase of the plan.
Understanding R0
To understand the next phase, we need to understand something very simple about how a virus spreads. An infected person will eventually recover or die. In that time, if they've caused more than one additional infection (on average), then the disease will continue to grow and spread. But if they've caused less than one additional infection, then the disease will shrivel away. This number - the number of additional persons that an infected person infects - is called R0, and for the coronavirus, if we do nothing, it's about 2-3. The goal of all our personal hygiene and social distancing efforts is to reduce this number, so that the infection dies down.
The other important thing to know about this number is that it succinctly expresses the entire power of the virus. If this value cannot be brought down below 1, then the virus will continue on its rampage until it inevitably infects a huge portion (~60% or so) of the population. This is the catastrophe we are trying to prevent. It is this scenario that holds all our fears. In contrast, the current numbers, as large as they seem, are trivial for a population our size. They're still "no worse than the flu", in the commonly misused phrase of a few weeks ago. What we're really worried about is how these these numbers will grow, under the assumption of exponential growth.
That is why we must break that assumption. We do that by reducing R0 < 1. In fact, I think "flatten the curve" is the wrong motto. It should have been "break the (exponential) curve". We must take those exponential hockey-stick growth curves of infection and death, and break them right in two - into the growth curve, and then the decay curve. Again, we do that by keeping R0 < 1. As long as it's kept below 1, then it doesn't matter what else we do: the infection will inevitably wither away.
Now, while the coronavirus can be suppressed in this way, the consensus expert opinion seems to be that complete eradication is basically impossible, especially without a vaccine. So even when we get over our current hump, we will continue to live with the reality that there will be new cases popping up, everywhere on the planet. The second part of the plan is to keep such cases suppressed, so that they don't simply reset us back to the beginning.
Phase 2: permanent R0 < 1
We continue the suppression by keeping a permanent environment of R0 < 1. But what does that mean, in practical terms? Does that mean a permanent state of lockdown? Not at all. The current lockdowns are necessary because we were basically caught flat-footed. They are drastic measures that reduce R0 down to values like 0.3 - far less than 1. We're implementing them because the possible impact to our health care systems needs to be reduced NOW, and we don't know what else to do. But with the time we have in this lull, we can think of new, efficient ways to reduce R0 - ones we can carry out easily and indefinitely.
Think of it this way: to reduce R0 from 2 or 3 to down below 1, we just need to reduce the chance of infection by 50-70%. Every little thing we're doing - hand washing, staying more than 6 feet apart, etc., helps reduce this value. We just need to find enough of such measures to reduce R0 by about 70%.
There's bound to be a relatively easy way to do this, without requiring full lockdowns. It may be as simple as "everyone wears a face mask". Consider: if the sick person's face mask reduces transmission rates by 50%, and the possible recipient also gets a 50% reduction from their face mask, that's a total of 75% reduction. R0 < 1. Done.
The numbers in the above example are made up, of course. But we will learn such numbers soon. If a face mask alone is not enough, maybe we'll need face mask plus face shield, or maybe face mask and gloves. But think of it: it may be that we can all go back to "normal", with a simple additional measure like "everyone wears face masks". Some combination of such cheap, easy measures should reduce R0 to below 1.
How do I know this is possible? Because South Korea is already doing it. They have the coronavirus well under control, and they've never had to do shut down whole cities to do so. And how will we know that this is working, once we get there? That's where the massive testing comes in. We will know whether we need to increase or decrease our suppression efforts, because we will actually have the testing data showing us the accurate infection level. Basically, the testing and the suppression efforts will form a negative feedback loop, where we take more stringent actions if the infection rate in the population is higher - all the way up to another lockdown if necessary - and we relax these measures when the infection rate is lower.
Phase 2 example
This gets us back to "normal" - admittedly with some light additional measures - in a matter of just several weeks. But another beauty of this plan is that it can be implemented anywhere, any time. You don't need to wait for the federal government to swoop in with some trillion-dollar plan to start.
Say, for instance, that you're a small city in a state with a low infection rate. Nobody in the city is known to be sick with the coronavirus. But everyone is panicking! It's all that the rest of the country can talk about! Should you lock down the whole city right now? That does seem to be overblown, no? With zero known cases in the city? But then, what should you do?
According to the plan, you're effectively already past phase 1 - the "lockdown" phase - so you should implement phase 2: permanent R0 < 1. If I were this city, I would take all the cheap precautions I can without interrupting daily life. These may include:
The usual measures:
Hand washing, don't touch your face, keep 6 feet apart from other people, cover your coughs, stay home if you're sick.
Some enhanced measures:
Everyone wears a face covering of some kind (face masks are currently in short supply and should be reserved for health care workers), with more extensive protection for those that meet many people. Frequent cleaning of all public surfaces (door knobs, elevator buttons, etc), hand sanitizers and paper towels near all such surfaces, daily cleaning of all crowded areas.
Some easy social distancing:
Staggered work hours to keep public transportation less crowded, restrictions on large gatherings, restrictions on building occupancy, encourage working from home, clear plastic partitions between parties in crowded spaces (school desks, restaurant tables).
Frequent health checkups:
Full testing is ideal - but falling short of that, frequent temperature checks. Frequent reports from hospitals on people coming in with potential coronavirus symptoms.
Again, I am not in public health, and the above list is mostly just off the top of my head. This is just an example. It isn't meant to be a strictly prescriptive list. But the point is that this hypothetical city will still be fully functional, while significantly reducing R0. And it can stay with these measures indefinitely, because they are not overly burdensome.
And when this city gets its first confirmed case of the coronavirus, it will be dealing with only a handful of other possible infections, instead of the dozens or hundreds that a single case may imply without any measures. They should then immediately put in heavier measures for a short time afterwards, and when things are back down to zero active cases, lift these measures again. In such a way, our society can persist indefinitely, with a mostly "normal" life, while keeping the virus suppressed.
Summary and Victory
So that's the plan: for areas that are heavily infected now, lock down until the infection rate gets low enough. That's phase 1. Then, implement enough measures to keep R0 < 1, while maintaining a functioning society. Test extensively to provide feedback, so that we know whether we're doing enough. Respond to the test results by adding or removing the measures, so that we can keep R0 < 1, while maximizing society's activities. That's phase 2.
The final victory will come with the development of a vaccine, or an effective treatment. But that is a long ways off. Meanwhile, we'll be just fine, carrying on with daily life with some additional measures - light measures that can be borne indefinitely.
A much more thorough explanation
Many of you will have already read or heard of Tomas Pueyo's excellent article, Coronavirus: The Hammer and the Dance. I highly recommend it. It covers essentially all the same things that this post does, plus some miscellaneous topics, and goes over all of them in more detail. In fact, when I first read it a few days ago, I said "that is EXACTLY the post I was going to write next for my blog" - and now here you are, reading that blog post. I decided to write this anyway, because I want to give these ideas the maximum possible exposure. It's the obviously correct path forward.
You may next want to read:
On the coronavirus
The coronavirus pandemic: status report on the United States
Another post, from the table of contents
The current state of things
Mere hours after I published my last article, the San Francisco Bay Area got a "shelter in place" order. Since then many other cities and states have followed up with similar orders. I haven't tracked all such measures, but much of the United States is now in some form of lockdown. I feel like the societal mood has very much changed, to where people are now, finally, taking this seriously.
We are approaching the endgame now. Where do we go from here? And how do we get things back to normal, as quickly as possible? Some people are fantasizing an apocalyptic future, where we stay locked in for months and venture into the virus-infected outside world only to fight over food and toilet paper. Is that what lies ahead? It's clear that our current level of suppression cannot persist indefinitely, but how will it end, and what will life look like when it does?
First, let's go over some good news. Lockdowns are easy to implement, and they work. Once every infected person infects fewer than one additional person on average (R0 < 1), the mathematics of the exponential function now work against the virus, and its numbers collapse with the same rapidity it had during its growth. South Korea and China had already broken the exponential growth long ago, and now, with the latest numbers, it looks like Italy has turned the corner as well, as I said it would.
The major population centers for the U.S (in particular the SF Bay area, where I live) should also reach this point in another week or so. There are other parts of the country where the virus started later, so they will be on a time-delay from the major cities. Again I can't keep track of the different levels of infection all across our vast and diverse country, but in any given area, once your city is in lockdown, the virus will die down in a matter of a few weeks.
What then? If we simply go back to normal, the virus will just flair up again, and we'd be right back to where we started. So does that mean we have to stay locked in indefinitely? That's clearly unsustainable. Fortunately, there's an easy way forward - one that is easy to implement, keeps the number of infections and deaths low, and restores us to mostly "normal life" in just a few weeks.
The way forward - phase 1: lockdown
First, we stay locked down until the worst passes. The healthcare systems are bracing for impact right now, and more infections now will worsen their caseloads and the outcomes for their patients. Stay in your homes, and help out your neighbors and local businesses while maintaining social distancing.
In the meantime, our testing capacity needs to increase massively. Things have certainly improved in testing since the botched initial rollout, but I believe we have much more to do. The rest of this plan hinges on accurately measuring the level of infection in the population, at each local level - every state and every city. We will need enough tests to detect infection levels like 0.01%, everywhere in the country.
In any case, with the lockdown, the numbers will decline. The medical professionals will get slammed for a short time and heroically fight their battles. They will come out victorious on the other side, because the virus will have been starved of new victims. At this point, we can start the next phase of the plan.
Understanding R0
 |
| R0 = 2. Every sick person infects two others, and the infection continues to grow. |
The other important thing to know about this number is that it succinctly expresses the entire power of the virus. If this value cannot be brought down below 1, then the virus will continue on its rampage until it inevitably infects a huge portion (~60% or so) of the population. This is the catastrophe we are trying to prevent. It is this scenario that holds all our fears. In contrast, the current numbers, as large as they seem, are trivial for a population our size. They're still "no worse than the flu", in the commonly misused phrase of a few weeks ago. What we're really worried about is how these these numbers will grow, under the assumption of exponential growth.
 |
| R0 = 1/2. Each person only has a 50% chance of passing on the virus, and the infection shrinks. |
Now, while the coronavirus can be suppressed in this way, the consensus expert opinion seems to be that complete eradication is basically impossible, especially without a vaccine. So even when we get over our current hump, we will continue to live with the reality that there will be new cases popping up, everywhere on the planet. The second part of the plan is to keep such cases suppressed, so that they don't simply reset us back to the beginning.
Phase 2: permanent R0 < 1
We continue the suppression by keeping a permanent environment of R0 < 1. But what does that mean, in practical terms? Does that mean a permanent state of lockdown? Not at all. The current lockdowns are necessary because we were basically caught flat-footed. They are drastic measures that reduce R0 down to values like 0.3 - far less than 1. We're implementing them because the possible impact to our health care systems needs to be reduced NOW, and we don't know what else to do. But with the time we have in this lull, we can think of new, efficient ways to reduce R0 - ones we can carry out easily and indefinitely.
Think of it this way: to reduce R0 from 2 or 3 to down below 1, we just need to reduce the chance of infection by 50-70%. Every little thing we're doing - hand washing, staying more than 6 feet apart, etc., helps reduce this value. We just need to find enough of such measures to reduce R0 by about 70%.
There's bound to be a relatively easy way to do this, without requiring full lockdowns. It may be as simple as "everyone wears a face mask". Consider: if the sick person's face mask reduces transmission rates by 50%, and the possible recipient also gets a 50% reduction from their face mask, that's a total of 75% reduction. R0 < 1. Done.The numbers in the above example are made up, of course. But we will learn such numbers soon. If a face mask alone is not enough, maybe we'll need face mask plus face shield, or maybe face mask and gloves. But think of it: it may be that we can all go back to "normal", with a simple additional measure like "everyone wears face masks". Some combination of such cheap, easy measures should reduce R0 to below 1.
How do I know this is possible? Because South Korea is already doing it. They have the coronavirus well under control, and they've never had to do shut down whole cities to do so. And how will we know that this is working, once we get there? That's where the massive testing comes in. We will know whether we need to increase or decrease our suppression efforts, because we will actually have the testing data showing us the accurate infection level. Basically, the testing and the suppression efforts will form a negative feedback loop, where we take more stringent actions if the infection rate in the population is higher - all the way up to another lockdown if necessary - and we relax these measures when the infection rate is lower.
Phase 2 example
This gets us back to "normal" - admittedly with some light additional measures - in a matter of just several weeks. But another beauty of this plan is that it can be implemented anywhere, any time. You don't need to wait for the federal government to swoop in with some trillion-dollar plan to start.
Say, for instance, that you're a small city in a state with a low infection rate. Nobody in the city is known to be sick with the coronavirus. But everyone is panicking! It's all that the rest of the country can talk about! Should you lock down the whole city right now? That does seem to be overblown, no? With zero known cases in the city? But then, what should you do?
According to the plan, you're effectively already past phase 1 - the "lockdown" phase - so you should implement phase 2: permanent R0 < 1. If I were this city, I would take all the cheap precautions I can without interrupting daily life. These may include:
The usual measures:
Hand washing, don't touch your face, keep 6 feet apart from other people, cover your coughs, stay home if you're sick.
Some enhanced measures:
Everyone wears a face covering of some kind (face masks are currently in short supply and should be reserved for health care workers), with more extensive protection for those that meet many people. Frequent cleaning of all public surfaces (door knobs, elevator buttons, etc), hand sanitizers and paper towels near all such surfaces, daily cleaning of all crowded areas.
Some easy social distancing:
Staggered work hours to keep public transportation less crowded, restrictions on large gatherings, restrictions on building occupancy, encourage working from home, clear plastic partitions between parties in crowded spaces (school desks, restaurant tables).
Frequent health checkups:
Full testing is ideal - but falling short of that, frequent temperature checks. Frequent reports from hospitals on people coming in with potential coronavirus symptoms.
Again, I am not in public health, and the above list is mostly just off the top of my head. This is just an example. It isn't meant to be a strictly prescriptive list. But the point is that this hypothetical city will still be fully functional, while significantly reducing R0. And it can stay with these measures indefinitely, because they are not overly burdensome.
And when this city gets its first confirmed case of the coronavirus, it will be dealing with only a handful of other possible infections, instead of the dozens or hundreds that a single case may imply without any measures. They should then immediately put in heavier measures for a short time afterwards, and when things are back down to zero active cases, lift these measures again. In such a way, our society can persist indefinitely, with a mostly "normal" life, while keeping the virus suppressed.
Summary and Victory
So that's the plan: for areas that are heavily infected now, lock down until the infection rate gets low enough. That's phase 1. Then, implement enough measures to keep R0 < 1, while maintaining a functioning society. Test extensively to provide feedback, so that we know whether we're doing enough. Respond to the test results by adding or removing the measures, so that we can keep R0 < 1, while maximizing society's activities. That's phase 2.
The final victory will come with the development of a vaccine, or an effective treatment. But that is a long ways off. Meanwhile, we'll be just fine, carrying on with daily life with some additional measures - light measures that can be borne indefinitely.
A much more thorough explanation
Many of you will have already read or heard of Tomas Pueyo's excellent article, Coronavirus: The Hammer and the Dance. I highly recommend it. It covers essentially all the same things that this post does, plus some miscellaneous topics, and goes over all of them in more detail. In fact, when I first read it a few days ago, I said "that is EXACTLY the post I was going to write next for my blog" - and now here you are, reading that blog post. I decided to write this anyway, because I want to give these ideas the maximum possible exposure. It's the obviously correct path forward.
You may next want to read:
On the coronavirus
The coronavirus pandemic: status report on the United States
Another post, from the table of contents
The coronavirus pandemic: status report on the United States
Introduction, disclaimer, and a call to actionSimilar disclaimer as the last time: I'm not a medical or a public health professional, but I am a data scientists. I deal with probabilities, statistics, and analyzing risks all the time. I've been looking at the coronavirus pandemic for some time now, looking at multiple sources of data. I consider myself to be well-informed, and my analysis to be sound. This is what I see, as of now (early morning hours of March 16th).
If we do nothing, this coronavirus will infect a large portion of the population (say, 50%), overwhelm our health care systems, and kill a significant portion of those it infects (say, 3%).
IF we do nothing, the numbers cited above results in 5 million deaths in the United States, and more than 100 million deaths worldwide. These numbers are so absurd that it doesn't even matter much if you somewhat disagree with my assumptions. You think the mortality rate will only be 1%, and only 25% will get it? It's still a complete catastrophe.
IF we do NOTHING, this will be the worst catastrophe in American history, and one of the worst in all of world history.
IF we do nothing.
IF.
The most important word in the above paragraphs is not "million", "death", or "catastrophe". It's "if". "IF we do nothing".
And that's why I DON'T think the above scenario will play out. But ONLY because we'll do something about it. We WILL ACT. We will not simply sit by and let one of the worst catastrophes in human history play itself out.
We will act to break the exponential propagation of the virus, limit its spread, and flatten its growth.
We will act to achieve what we already know is possible: China and South Korea have already broken the exponential growth of the virus, and they have successfully limited its spread to a tiny portion of their population. With any luck, Italy will soon see similar results, on the time scale of a couple of weeks (the incubation period of the virus).
We will act to save people, and bring our daily life back to normal as soon as possible. If we act strongly enough, it's still possible to keep the deaths below the numbers from last year's flu. Even if we have three major American cities blow up like Wuhan, that's still only about 10,000 deaths. And we will all be able to look back on this as merely a short, interesting time in our history.
But only because WE WILL ACT.
Looking into the future
To be sure, we have already taken some actions. But we're all wondering whether we've done enough, and how things will turn out in the future. After all, it's the future that's scary: people often report and comment on the current numbers, but I think this is a mistake. The current numbers, of themselves, are insignificant. It's what they portend for the future, under the assumptions of exponential growth, that's the cause for alarm. That's why it's so important to break the exponential, through our efforts of social distancing and better personal hygiene.
But will we succeed? Well, we are fortunate in this regard, because we can, in effect, look into the future. There are a number of countries that contracted this infection before the United States, and they're correspondingly ahead of us in the virus's growth curve. By examining these countries, we can effectively look at the multiple-choice future presented before us.
Taiwan is an ideal case: They've effectively succeeded in keeping the virus out of their country, and it's never reached significant numbers there. Of course, this scenario is closed off for the United States now. It's too late.
South Korea is also a really good case. They had a significant outbreak, but they've successfully broken the exponential, and their number of cases are flattening out. And they did it without having to lock down an entire city - instead using measures like contact tracing, aggressive testing, and tracking personal data.
China has also successfully broken the exponential growth, and they have very few new daily cases now. They did have to lock down Wuhan and several other cities to achieve this. This draconian measure is widely considered to have been a right, necessary move, although it might not have been necessary at all if the CCP didn't cover up the initial reports of the infection.
Italy locked down their whole country just a few days ago. Like in Wuhan, their health care system was overwhelmed, and their mortality rate is exceptionally high. Hopefully, they'll begin to see the results from the lockdown soon.
Meanwhile, Iran is digging mass graves. Reliable numbers from there are hard to come by.
So, those are the range of possible futures for the United States. Which one will we take? That depends on what we've done so far, and how we'll act going forward. Have we done enough? Should we do more?
United States status report
Here, I'm going to give a VERY ROUGH estimation of where I think we are, and whether we're doing enough. In the absence of other, more specific information, this could help you to inform your actions.
But again, I am not a medical or public health professional. I'm basing this only on broad, mostly publicly available data. If any local government or health authority gives out any specific information, advice, or order that contradicts anything I have to say below, please listen to them instead of me.
One thing that needs to be addressed right away is the appalling failure of testing in the US. This makes everything more confusing, and it means that we're significantly under-reporting the true number of cases, even compared to other countries. This makes everything harder, everything worse.
However, some people have used this as an excuse to postulate that there are a truly vast number of undetected cases out there. I am not much moved much by such a postulate, for two reasons: 1) I find it unlikely, and 2) if true, it would actually be good news in an unexpected way.
First, I find it unlikely because the number of deaths here in the United States have are still fairly limited - and deaths are much less likely to go undetected. Again looking at the data across countries, we see that the US has about the same number of deaths as South Korea. And we know that South Korea has 1) had extensive testing, and 2) has the infection mostly under control. So their number of reported cases must be somewhat close to the number of true cases. This implies that if the US also had extensive testing, we'd also have roughly 8000 reported cases, and that the total cases would not be too much larger than that, order-of-magnitude wise. You can do a more sophisticated calculation taking into account things like doubling time and time-to-death, but I don't think the numbers will change very much for this order-of-magnitude calculation. The United States probably has something like 20,000 - 90,000 actual cases, but probably not 500,000 or a million. Other estimates, for example from this excellent article, also puts the estimates at 5 to 30 times the number of reported cases, in its estimates from San Fracisco Bay Area, Washington state, and Wuhan.
Secondly, if we really did have a million undetected cases, then that would actually be good news, because that would imply a very low mortality rate for the virus. Apparently most of these million people were largely asymptomatic and never in any real danger of dying. This remains true even if you back out the typical time-to-death after contracting the virus. A million undetected cases, after backing out the time to mortality, would imply a mortality rate of about 100 deaths / 100,000 cases = 0.1%. That would mean we can go back to treating this like a bad flu.
So, the most cautious and reasonable approach would be to assume roughly 10 times the reported number of cases. This is good enough for my rough, order of magnitude calculations below, and I'll proceed with that number going forward.
Other numbers I'll use here are:
2% mortality rate, multiplied by 3.5 to account for the mortality of the 2.5 other people you're likely to infect. So if you get infected, the chance of you dying, or directly getting someone killed, is roughly 7%.
15% of active cases generate new cases every day, if we do nothing. This is in accord with a doubling time of 5 days, and a R0 of about 2.5.
Then your personal risk of causing death - your own or the ones you directly infect - on a given day can be estimated by:
fraction of population that's reported to be infectedAll this again assumes we do nothing to avoid infection. These number and calculations are, again, rough, but they're serviceable for an order-of-magnitude estimation. Note that there's a single parameter that largely determines how bad things are - the fraction of population that's reported to be infected.
* 10 (to account for true vs. reported cases)
* 0.15 (15% growth rate per day)
* 0.07 (chance of causing death, given infection)
Let's work through how things change as we increase this number. This will tell you how much danger you're in, and whether you're doing enough. Again I remind you that this is only a ROUGH ESTIMATE, under the assumption that we do nothing, and that you should defer to any information from local governmental and health authorities.
But with all that said, if the fraction that's reported to be infected in your city is:
0.0001%
At this level, your daily risk of causing death is about 1 in 10 million. This is less than your chance of dying in a car accident in a given day (1 in 3 million)
So there isn't a whole lot of risk to your personal safety at this level. The risk is less than driving. But you should still pay attention, stay vigilant, and prepare. Governments, being larger than individuals, needs to start acting at this level or sooner, because If we do nothing, in just a few weeks, the fraction will become...
0.001%
Daily risk of causing death: 1 / 1 million.
Other fatality rates for reference:
car accident: 1 / 3 million days
sky diving: 1 / 160,000 jumps.
sky diving has about the same life-expectancy loss as smoking a pack of cigarettes.
You should definitely take personal precautions at this stage, beyond just "wash your hands" and "don't cough on people". After all, when you drive, you put on a seat belt and make sure you're not drunk or tired. You put your kids in a car seat. You get insurance, and pay thousands of dollars for extra safety features on your car. But at 0.001%, if we do nothing, the level of danger due to the coronavirus is distinctly higher than just driving.
America, as a whole, is at this level (4000 cases / 330 million population = 0.001%). But your numbers for your city are more important. They'll affect you more directly.
Los Angeles county is slightly below this level (70 cases / 10 million = 0.0007%. All local case numbers come from here).
The state of New York, and the San Francisco Bay Area, are both ABOVE this level (700 cases / 20 million population = 200 cases / 7 million population = 0.003%). Santa Clara - the hardest hit county in the Bay Area - is higher still, at 0.005%. In these areas, going about your day normally, without any precautions, is about as dangerous as skydiving. Would you go out to eat if you had to skydive to get there? And smoke a pack of cigarettes on your way back? Then don't go out. I personally have started working from home. If you must leave your house, take a LOT of precautions.
If we do nothing, in a just few weeks, the fraction will become...
0.01%
Daily risk of causing death: 1 / 100,000
about the same life-expectancy loss as smoking 2 packs of cigarettes.
Wuhan went into lockdown at around this level (1000 cases / 10 million population = 0.01%). This makes perfect sense: As a city leader, if every citizen in your city started smoking 2 packs a day, would you not do something? Especially when faced with the prospect that this number will double every 5 days or so?
Another way to think about it is that this is the last level where some kind of "normal" life is possible. The levels above this one - 0.1% and above - rapidly approach the worst case scenario I described at the very beginning, where a good chunk of your population dies. 0.1% reported infection rate would mean about a 1% actual infection rate, and it's hard to see how you can stop that from growing to a significant portion of the population. So there isn't a whole lot of time left at this 0.01% level. Drastic actions are required.
Seattle (King and Snohomish counties) is ABOVE the 0.01% level (460 cases / 3 million population = 0.015%). Meaning, the ONLY thing that'll keep Seattle from going Wuhan is its social distancing/personal hygiene efforts up till now.
Has that been enough? Well, in order to break the exponential, the R0 (reprorductive number for coronavirus) needs to drop from 2 - 2.5 down to below 1: that is, a reduction to 50%-40% of its normal value. Everyone needs to reduce their chance of infection to those values, through social distancing or better personal hygiene. Now I've looked at some data on this, and it seems like Seattle is just at the cusp of that 50%-40% value: that is to say, SEATTLE MAY NOT BE DOING ENOUGH. No American city is doing enough yet, but at least the other cities have a little more time. For Seattle, the time for drastic action is NOW.
I'll not say whether Seattle needs to go into total lockdown, like Wuhan or Italy. I remind everyone that this is only a rough estimation, made under the assumption that we do nothing. And Seattle has certainly been doing things. They're engaged in extensive social distancing measures, and many of their citizens are aware of what's at stake. But even that may not have been enough. Right now, every option - including total lockdown - should very much be on the table for Seattle.
For the rest of America - watch Seattle. Pay very close attention. Remember, this is effectively looking a couple weeks into our future. If it turns out that Seattle hasn't done enough, then we'll all know that we need to redouble our efforts.
Italy, as a whole, is distinctly above this level (25,000 cases / 60 million population = 0.04%). It's not at all surprising that they shut the whole country down.
If we do nothing, in just a few weeks the fraction will become...
0.1%
Daily risk of causing death: 1 / 10,000
Taking on this level of risk every day is very likely to cause a premature death (on the order of 50%). This is therefore a completely unacceptable level of risk, and any city or country that finds itself in this situation needs to do everything they can to get themselves out.
If we do nothing, in just a few weeks the fraction will become...
1%
Daily risk of causing death: 1 / 1000
This is effectively the worst case scenario detailed at the beginning of this post. A big chunk of your population will die. Everyone keeps saying "don't panic", but if ever there is a time to panic, this would be it.
Status summary
An important takeaway here is how quickly we progress up these levels IF WE DO NOTHING. From 0.001% (where we are as a country) to 0.01% (where cities and countries start shutting down) is only a matter of weeks. Seattle is there already. And if we go much above that, we quickly approach the completely unacceptable, worst-case scenario.
Another important takeaway is that no American city may be doing enough. We need to break the exponential growth. We need to reduce R0 - from 2 or 2.5, down to below 1. That's a reduction to 50%-40% of its normal value. My best guess right now is that we're hovering around 50% in our major cities - not enough to be certain of breaking the exponential. Seattle is taking this the most seriously, but they also have the least time.
It may be that Seattle turns out to be an example and a warning to the rest of the American cities. It may need to completely lock down, and that may cascade into other cities to taking equally drastic measures.
But now is still not the time to panic. Keep calm. Stay safe and healthy. And take the necessary actions to safeguard yourself and your community.
You may next want to read:
On the coronavirus
The intellect trap
Another post, from the table of contents
On the coronavirus
 |
| https://www.worldometers.info/coronavirus/country/us/ |
I'm not in healthcare or public health, but I do analyze data for a living. Things like probabilities, managing risks, and statistics are my bread and butter. I've been tracking the data on this coronavirus thing for some time now, using multiple sources of data, and calculating the risk to my personal life and health.
I live in the San Francisco Bay Area. This week (starting 3/9) is the first week when my personal risk will become unacceptably high for me. Furthermore, this risk will continue to increase at an incredibly rapid rate, (very) roughly doubling every 4 days or so.
"Unacceptably high" doesn't mean that I expect to drop dead this week. It just means that it's distinctly higher than the other risks that I would take without thinking, like driving.
But even while driving, you take basic precautions, like wearing a seat belt, and making sure that you're not sleepy or drunk. Right now, for me, going out in public without precautions is about as dangerous as driving. It's probably distinctly worse. And getting riskier very rapidly.
This risk is calculated for me personally - taking into account things like my age and health, who I interact with, where I live and work, etc. It may not directly apply to you. But soon enough, it likely won't matter. If you live in an area with a known infection, the exponential growth of the virus means that it will quickly catch up with your personal threshold as well, in a matter of days or weeks.
This doesn't mean that anyone should panic, of course. You wouldn't panic over someone not wearing their seat belt, or lighting up a cigarette. But you'd clearly agree that these are bad ideas. And, again, the risks here increase exponentially with time. Soon enough it will be like getting in a car with a drunk driver. Without a seat belt. On a stormy night. For a drag race.
For those of you in the San Francisco Bay Area, this means that now is the time to act. And I don't mean that as a platitude, in the "no time like the present" or "seize the day" sense. I actually mean that now - the week of 3/9 - is the time when you should start to significantly change your personal behavior, beyond just washing your hands and not coughing on people. Before this week, it wasn't irrational for a private citizen, concerned only with his own health, to go about his day normally. As of this week, this is no longer the case. This is the week that the risk becomes actionably meaningful.
Again, for now, this doesn't mean that everyone needs to be locked into their houses right away. But week by week, the magnitude of the required precautions will increase significantly. If we were to implement zero precautions, we'd be looking at the "complete shutdown" scenario in a matter of a few weeks.
Regardless of where you are, your risk will increase until the outbreak is contained in your area. For now, the only way to do that is for enough people to take enough precautions. As a population, the longer we wait the more dramatic and painful these "precautions" will need to be, up to and including a complete shutdown of your city or region, like they did in Wuhan.
I'm continuing to go to work, and continuing with most of my daily routines for now - but with lots of extra precautions. My current rule of thumb is that I'll take any precaution that's easier than putting on a seat belt. I'll probably start working from home fairly soon - I'm running the numbers daily to see when that is. If you want to see the math, I'd be glad to go over it with you.
But in any case, take this thing seriously, and stay calm, safe, and healthy.
You may next want to read:
Basic Bayesian reasoning: a better way to think (Part 1)
The intellect trap
Another post, from the table of contents
The Gospel according to "Frozen II" (or, why Elsa is Jesus) (edit 5)
I'm still in the middle of writing The Gospel according to "Frozen II" (or, why Elsa is Jesus). I'm done with the rough draft, and now begins the iterative process of revising and editing. I think I may finish by next week if I'm lucky.
You may next want to read:
A systematic mythology of the "Frozen" universe
The Gospel according to Disney's "Frozen"
Another post, from the table of contents
You may next want to read:
A systematic mythology of the "Frozen" universe
The Gospel according to Disney's "Frozen"
Another post, from the table of contents
The Gospel according to "Frozen II" (or, why Elsa is Jesus) (edit 4)
I'm still in the middle of writing The Gospel according to "Frozen II" (or, why Elsa is Jesus). Again, this is turning out to be a difficult project, but I'm making good progress.
You may next want to read:
A systematic mythology of the "Frozen" universe
The Gospel according to Disney's "Frozen"
Another post, from the table of contents
You may next want to read:
A systematic mythology of the "Frozen" universe
The Gospel according to Disney's "Frozen"
Another post, from the table of contents