Still standing by this: Covid-19: My Current Model

Previous update posts: Covid-19 5/29: Dumb ReopeningCovid 5/14: Limbo Under

Remember last week when I opened with this?

I remember when people on Twitter had constant reminders that today was, indeed, only Wednesday, or whatever day it happened to be. Time moved that slowly.

Time has sped up again.

Well, yeah. Not so much anymore.

In March and April I found myself constantly checking Twitter and the financial markets for news, frantically hunting for ways to get a handle on what was happening in the world, worried everything would fall apart. Would our supply chains hold? Would we be able to maintain civil order? Would millions die? How can I keep my family and friends safe?

My beloved New York City was no longer a place one could live a reasonable life. So we fled. Even after that, great worry.

Then things started to calm down. Most of May, I increasingly managed to relax. We learned how to grill properly. I played a bunch of Assassin’s Creed Odyssey. I stopped checking Twitter or the stock market.

My biggest worries were dealing with getting the Emergents Alpha ready and Magic: The Gathering melting down under the weight of the companion mechanic in particular and its new design philosophy in general.

End of the Beginning

Then, on May 25, 2020, in Minneapolis, four policemen murdered George Floyd.

The resulting cycle of protests against police brutality causing more police brutality, which in turn amplifies the protests, has been ongoing each day since then. Huge crowds flood the streets. The crowds come disproportionately from communities with more Covid-19 cases than average. The crowds often yell. The police use tear gas on them, which causes coughing. The police arrest them and lock them in tight quarters, which is going to spread the virus even if the outdoor activities don’t, hopefully in small enough numbers this isn’t a huge deal.

To the extent other things are also happening, that only makes the infection situation worse.

It would be very surprising if all this did not lead directly to a surge of new Covid-19 infections.

It would also be very surprising if all this did not lead indirectly to a much bigger surge of new Covid-19 infections.

Effectively, the lock down is over.

Nuance is hard in the best of circumstances. The community I know who got most ahead of the game on Covid-19, the Rationalist community, is still so bad at nuance that one of its de facto community leaders felt he could not go anywhere or do anything during the epidemic. Because if he did, others would not be able to properly parse his actions as responsible, or be able to choose responsible actions themselves, and all quarantine would collapse for everyone..

These are not the best of circumstances.

People have seen, and will continue to see, the photos and videos of gigantic crowds in the streets. They will see the approval of those crowds, by the exact same people who told them they should face a depression and 30% unemployment to fight Covid-19. The same people who told them they should not see family and friends and live their lives.

Even those who support the protests are going to have a very, very hard time taking extreme restrictions seriously going forward. Life beckons.

For those who don’t support the protests, forget about it.

There is no going back. Either people’s private choices, after the resulting adjustments in perception of risk, based on their local desire to keep themselves and their communities safe, will still be enough to contain this virus. Or, we will entirely fail to contain this virus until herd immunity provides enough help to turn the tide.

I cannot think of a more just cause then stopping state-sanctioned murder. That does not make these implications go away.

That is where we are going to be. We are probably going to see a massive dumb reopening, much faster and more complete than previously predicted or planned. That is the world we now live in.

I don’t know if I even think that these effects are bad.

This could all work out for the best.

It could work out because we contain the virus anyway. I don’t expect it, but it’s definitely plausible.

It could also work out because we were never going to successfully contain in most places without stronger herd immunity – regardless of whether we could have done so given better policy – and this gets us there faster and by infecting a relatively young subset of the population. Also definitely plausible.

Or it could work out because outdoor events don’t matter, and this leads to lots more things happening outdoors but not indoors, so we move to a better world no matter the outcome. This, too, seems plausible to me.

Our, it could work out because enough people adjust their behaviors to stay home more, because they predict a second wave, and this cancels out or more than cancels out the direct effects above. You never know.

How long before we know the results?

It has been over a week since things were set in motion. The first few days were relatively small. Events didn’t start having their full impact until at least the last few days. They may not have reached anything like their peak yet. And if the virus is now spreading in a particular sub-population, we may see exponential growth within that particular sub-population, over the course of several cycles of infection. So the effect might be small at first, then only look large weeks later.

Secondary effects, from others adjusting behaviors, will also be gradual and delayed.

On top of any lag of the actual infections, the time from infection to positive test has always been an open question. My guess is it is currently an average of seven days.

In the meantime, what was happening before all this?

The Numbers

Positive test results by region:

Mar 19-Mar 25 4283 4103 5045 4955 19925
Mar 26-Apr 1 14962 18641 22823 31631 54920
Apr 2-8 17170 25899 32296 46365 54894
Apr 9-15 17393 30403 39118 63548 64342
Apr 16-22 17149 32804 32926 61955 52481
Apr 23-29 22958 39570 33974 65682 44484
Apr 30-May 6 22269 49256 37503 53803 26957
May 7-May 13 23612 43429 36280 43952 18102
May 14-May 20 22594 44054 40556 37567 14316
May 21-May 27 23595 41635 42679 32762 11393
May 28-June 3 30094 32216 46848 24926 8947

Deaths by region:

Mar 19-Mar 25 138 104 144 116 278
Mar 26-Apr 1 380 615 572 606 1656
Apr 2-8 707 1454 1309 2115 4327
Apr 9-15 890 2195 1596 3577 5318
Apr 16-22 1033 2343 1727 5147 3716
Apr 23-29 1128 2588 1685 4722 2713
Apr 30-May 6 1012 2413 1747 4908 2582
May 7-May 13 1082 2288 1597 3911 1416
Apr 23-29 1090 2060 1442 3578 963
Apr 30-May 6 775 1723 1290 2341 667
May 28-June 3 875 1666 1387 2121 436

Positive test percentages:

Date USA tests Positive % NY tests Positive %
Mar 19-Mar 25 347577 16.2% 88,882 32.0%
Mar 26-Apr 1 728474 20.2% 117,401 45.1%
Apr 2-8 1,064,225 19.8% 144,273 45.5%
Apr 9-15 1,026,741 20.4% 160,859 40.1%
Apr 16-22 1,235,393 16.1% 143,970 30.2%
Apr 23-29 1,552,560 13.0% 202,499 21.0%
Apr 30-May 6 1,759,548 10.6% 183,446 13.2%
May 7-May 13 2,153,748 7.5% 202,980 8.2%
May 14-May 20 2,643,333 6.0% 246,929 5.6%
May 21-May 27 2,584,265 5.7% 305,708 3.5%
May 28-June 3 3,022,470 5.1% 417,929 2.2%

New York had been winning its war. On June 2 there was a scary jump in positive test rates. That was especially scary as it could have represented Memorial Day. But the trend was back on course again on June 3, so things were probably fine at least until the protests.

New York continues to reopen. On a personal level, they are allowing outdoor dining here in a few days, and full restaurants a week later. For all practical purposes the limiting factors on my behavior will be my own risk considerations, not official restrictions. I was training myself to stop sweating the small stuff, and prepare to go out more and more into the world. Now it’s much less clear that’s going to happen.

The Northeast in general continues to do well, but not as well as New York.

The rest of the country is still a more mixed bag. The Midwest is encouraging and a welcome surprise, enough to make overall numbers move in the right direction. But the jump in cases out West is troubling. It is spearheaded by California, with most Western states seeing a marked jump. The South also continues to creep upwards, especially Texas, South Carolina and Virginia. It’s worth noting that Florida and Georgia saw declines, so unless they’re fudging the data this isn’t about speed of legal reopening.

The death counts aren’t changing much, as one would expect given their lag. They are listed as a valuable sanity check, but the three week or more delay is fatal to them usually providing the key new information in a given week. By comparing the two charts, we can see exactly how delayed. If anything, it’s a big mystery that the deaths move way too much in lockstep with cases, rather than on a delay. Is this that case diagnosis is more delayed than seems reasonable, or is under bad circumstances? Or is it something else?


Thus, this week’s update was mostly speculation about the future.

Please keep the comments section confined to Covid-19 considerations.

Watching the positive test counts over the next few weeks will be crucial to figuring out our new path, as we also determine the path of our nation in other ways.

New York is seeing major protests, and had a very clear improving trend line, with very good plentiful on-demand testing. I think it’s a very good place to look to see the delta from recent events, as it’s one place where we know the prior score.

If New York continues to make similar progress for two weeks, then the protests are not very dangerous as a primary effect. Even one full week of the same trend line would be enough to be pretty confident this effect is not large.

If New York quickly stops making progress, or even reverses, we have to assume that the primary impacts are very dangerous.

Neither of these tells us much about secondary adjustments. Those will be gradual. People are creatures of habit. Many of them are also scared of going outside given the unrest. In the short run, this likely works the other way. We won’t know what the real impact of the unrest is upon the curve, until there is less unrest. And that long term trend is what matters.

If we do have a second wave, estimating the impact of partial herd immunity will determine the path forward. If I am right that New York’s advantage over other areas is mostly its larger herd immunity, and I’m also right that it is making up for otherwise relatively unsafe circumstances rather than Cuomo having delivered the goods on that front, then that’s very good news. We should see similar actions result in shrinking R0 over time.

However, note that this will be a delayed effect. First, in places with very little immunity, we will instead have the opposite effect. As the new normal sets in, people’s choices in the new normal determine their risk level, and the more risky are infected more. As this takes effect, things look like they are getting worse, even as the groundwork is laid – by making those risky people immune – for things to get better later. Or so we hope. We can even view ‘New York City gets very infected’ as a geographic example of the exact same thing. For a while it made the nation’s epidemic seem much worse than it was. But that concentration of risk made our long term prospects much better.

Ultimately, I continue to be an optimist of sorts on this, but with little confidence.

As discussed above, it’s doubtful the United States has much state capacity left to take meaningful action against Covid-19. It’s up to the individuals now, even more than it seemed to be a week ago.

The die has been cast. The only question is what number it lands on.



New Comment
7 comments, sorted by Click to highlight new comments since:

From Facebook:

Jai Dhyani: This seems like an extremely overconfident prediction and I don't think it accurately reflects popular opinion regarding pandemic response.

Rob Bensinger: What are the main things you think Zvi's wrong about? What do you think will happen?

Jai Dhyani: A series of predictions to which I assign each individually 75%+ chance: Social distancing is going to remain popular. Reopening will continue at a slow and steady pace. Large indoor gatherings will continue to be mostly avoided. Continued increases in testing capacity will slow spread and dramatic outbreaks, if they happen, will trigger the return of more aggressive measures with popular support. Masks will range between commonplace to mandatory in potentially risky contexts, and this will significantly slow spread. Coronavirus will return to being the dominant news story by the fall. US infections will continue to increase, but slowly. We will not approach herd immunity in the US in 2020.


I think the one I disagree with is "Continued increases in testing capacity will slow spread and dramatic outbreaks, if they happen, will trigger the return of more aggressive measures with popular support. " At least for realistic values of dramatic.

As I say explicitly, but perhaps not clearly enough, I'm highly uncertain whether the default level of response that we both kind of expect will be sufficient to beat this thing. I actually think it probably will be relatively fine, but with very low confidence.

The thing this expresses confidence in is that we've lost the state capacity to do anything to alter the course of events, other than somewhat slowing down the pace of reopening, should things not work out. That doesn't mean everyone will party like it's 2019. Whether the new normal is good enough, we'll find out.

It's good feedback that I come off as being much more confident of more things than I meant to express!

Any chance you could start including graphs rather than tables in your covid posts? :) 


I'll consider it. I find graphs more useful myself, so consider this a request to see what others think. Could also do both.

not as well as New York.

I take issue with the use of the word "well" in relation to the debacle in New York, past or current.

Taiwan; 0.3 deaths per million total, 1 death / 24 million in the last month

Australia 4 deaths per million total. 7 deaths / 25 million in the last month.

New York State: 1,550 deaths / million total. 5,000 deaths per 9 million in the last month. To compare to Taiwan or Australia it would be 12,000/25 million in the last month. Let the scale of that failure sink in.

New York's current *daily* death rate (10/million) exceeds Australia's total across the whole pandemic.

I see no evidence of herd immunity being a significant factor yet. I see no indication that things are under control.

Impact of the demonstrations.

I don't know the numbers of people in the demonstrations, let's say 100,000. Let's say 3% get infected as a result. That would be 3,000, significantly more than the reported daily new cases of ca 1,000. However given a ratio of 10% for deaths to reported cases, it is evident that reported cases are massively understated, perhaps 10 fold. Even so 3,000/(10*1,000)= 30% is a significant increment on the daily case load. And the people infected in the demonstrations may be people who might not have been infected in more normal circumstances.

[Rest of the comment moved to Open Thread]

Mod note: I decided to move the second half of this comment to the Open Thread, because Zvi explicitly requested that comments should stay on-topic. Here is a link to the new comment.

I attempted to produce a rough estimate of this here (excerpted below):

... One (BERI funded!) study suggested that banning large gatherings reduced r0 by around 28%.
Unfortunately, protests seem in many ways ideal for spreading the disease. They involve a large number of people in a relatively small area for an extended period of time. Even protests which were advertised as being socially distanced often do not end up that way. While many people wear masks, photos of protests make clear that many do not, and those that are are often using cloth masks that are significantly less effective than surgical or n95s in the face of repeated exposure. Additionally, protests often involve people shouting or chanting, which cause infectious droplets to be released from people's mouths. Exposure to tear gas can apparently also increase susceptibility, as well as cramped indoor conditions for those arrested.
It's hard to estimate how many new cases will be caused by the protests, because there doesn’t seem to be good statistics on the number of people at protests, so we can't model the physical dynamics easily. A simple method would be to assume we have lost the benefits of the ban on large gatherings over the last week or so. On the one hand, this may be an over-estimate, because fortunately most people continue to socially distance, and protests take place mainly outside. On the other hand, protesters are actively seeking out (encouraging others to seek out) boisterous large gatherings in a way they were not pre-March, which could make things even worse. On net I suspect it may under-estimate the incremental spread, but given the paucity of other statistics we will use it as our central scenario.
If the r0 was around 0.9 before, this suggests the protests might have temporarily increased it to around 1.25, and hopefully it will quickly return to 0.9 after the protests end. Even if we assume no chain infections during the protest - so no-one who has been infected at a protest goes on to infect another protester - this means the next step in disease prevalence would be a 25% increase instead of a 10% decrease. Unfortunately the exponential nature of infection means this will have a large impact. If you assume around 1% of the US was infected previously, had we stayed on the previous r0=0.9 we would end up with around 9% more of the population infected from here on before the disease was fully suppressed. In contrast, with this one-time step-up in r0, we will see around 12.5% of the population infected from here - an additional 3.5% of the population.
Assuming an IFR of around 0.66%, that's a change from around 190,000 deaths to more like 265,000. Protesters skew younger than average, suggesting that this IFR may be an over-estimate, but on the other hand, they are also disproportionately African American, who seem to be more susceptible to the disease, and the people they go on to infect will include older people.