Eastern Countries
South Korea cases have exploded, but have you wondered why Japan, Taiwan, Singapore, Thailand or Hong Kong haven’t?
Taiwan didn’t even make it to this graph because it didn’t have the 50 cases threshold that I used.
All of them were hit by SARS in 2003, and all of them learned from it. They learned how viral and lethal it could be, so they knew to take it seriously. That’s why all of their graphs, despite starting to grow much earlier, still don’t look like exponentials.
So far, we have stories of coronavirus exploding, governments realizing the threat, and containing them. For the rest of countries, however, it’s a completely different story.
Before I jump to them, a note about South Korea: The country is probably an outlier. The coronavirus was contained for the first 30 cases.
Patient 31 was a super-spreader who passed it to thousands of other people. Because the virus spreads before people show symptoms, by the time the authorities realized the issue, the virus was out there. They’re now paying the consequences of that one instance. Their containment efforts show, however: Italy has already passed it in numbers of cases, and Iran will pass it tomorrow (3/10/2020).
Washington State
You’ve already seen the growth in Western countries, and how bad forecasts of just one week look like. Now imagine that containment doesn’t happen like in Wuhan or in other Eastern countries, and you get a colossal epidemic.
Let’s look at a few cases, such as Washington State, the San Francisco Bay Area, Paris and Madrid.
Washington State is the US’s Wuhan.The number of cases there is growing exponentially. It’s currently at 140.
But something interesting happened early on. The death rate was through the roof. At some point, the state had 3 cases and one death.
We know from other places that the death rate of the coronavirus is anything between 0.5% and 5% (more on that later). How could the death rate be 33%?
It turned out that the virus had been spreading undetected for weeks. It’s not like there were only 3 cases. It’s that authorities only knew about 3, and one of them was dead because the more serious the condition, the more likely somebody is to be tested.
This is a bit like the orange and grey bars in China: Here they only knew about the orange bars (official cases) and they looked good: just 3. But in reality, there were hundreds, maybe thousands of true cases.
This is an issue: You only know the official cases, not the true ones. But you need to know the true ones. How can you estimate the true ones? It turns out, there’s a couple of ways. And
I have a model for both, so you can play with the numbers too (
direct link to copy the model).
First, through deaths. If you have deaths in your region, you can use that to guess the number of true current cases. We know approximately how long it takes for that person to go from catching the virus to dying on average (
17.3 days). That means the person who died on 2/29 in Washington State probably got infected around 2/12.
Then, you know the mortality rate. For this scenario, I’m using 1% (we’ll discuss later the details). That means that, around 2/12, there were already around ~100 cases in the area (of which only one ended up in death 17.3 days later).
Now, use the average doubling time for the coronavirus (time it takes to double cases, on average). It’s
6.2. That means that, in the 17 days it took this person to die, the cases had to multiply by ~8 (=2^(17/6)). That means that, if you are not diagnosing all cases, one death today means 800 true cases today.
Washington state has today 22 deaths. With that quick calculation, you get ~16,000 true coronavirus cases today.
As many as the official cases in Italy and Iran combined.
If we look into the detail, we realize that 19 of these deaths were from one cluster, which might not have spread the virus widely. So if we consider those 19 deaths as one, the total deaths in the state is four. Updating the model with that number, we still get ~3,000 cases today.
This approach from
Trevor Bedford looks at the viruses themselves and their mutations to assess the current case count.
The conclusion is that there are likely ~1,100 cases in Washington state right now.
None of these approaches are perfect, but they all point to the same message: We don’t know the number of true cases, but it’s much higher than the official one. It’s not in the hundreds. It’s in the thousands, maybe more.
San Francisco Bay Area
Until 3/8, the Bay Area didn’t have any death. That made it hard to know how many true cases there were. Officially, there were 86 cases. But the US is vastly undertesting because it doesn’t have enough kits. The country decided to create their own test kit, which turned out
not to work.
These were the number of tests carried out in different countries by March 3rd:
Sources for each number here
Turkey, with no cases of coronavirus, had 10 times the testing per inhabitant than the US. The situation is not much better today, with
~8,000 tests performed in the US, which means
~4,000 people have been tested.
Here, you can just use a share of official cases to true cases. How to decide which one? For the Bay Area, they were testing everybody who had traveled or was in contact with a traveler, which means that they knew most of the travel-related cases, but none of the community spread cases. By having a sense of community spread vs. travel spread, you can know how many true cases there are.
I looked at that ratio for South Korea, which has great data. By the time they had 86 cases, the % of them from community spread was 86% (86 and 86% are a coincidence).
With that number, you can calculate the number of true cases. If the Bay Area has 86 cases today, it is likely that the true number is ~600.
France and Paris
France claims 1,400 cases today and 30 deaths. Using the two methods above, you can have a range of cases:
between 24,000 and 140,000.
The true number of coronavirus cases in France today is likely to be between 24,000 and 140,000.
Let me repeat that: the number of true cases in France is likely to be between one and two orders or magnitude higher than it is officially reported.
Don’t believe me? Let’s look at the Wuhan graph again.
Source: Tomas Pueyo analysis over chart and data from the
Journal of the American Medical Association
If you stack up the orange bars until 1/22, you get
444 cases. Now add up all the grey bars. They add up to ~12,000 cases. So when Wuhan thought it had 444 cases, it had 27 times more. If France thinks it has 1,400 cases, it might well have tens of thousands
The same math applies to Paris. With ~30 cases inside the city, the true number of cases is likely to be in the hundreds, maybe thousands. With 300 cases in the Ile-de-France region, the total cases in the region might already exceed tens of thousands.
Spain and Madrid
Spain has very
similar numbers as France (1,200 cases vs. 1,400, and both have 30 deaths). That means the same rules are valid: Spain has probably upwards of 20k true cases already.
In the Comunidad de Madrid region, with 600 official cases and 17 deaths, the true number of cases is likely between 10,000 and 60,000.
If you read these data and tell yourself: “
Impossible, this can’t be true”, just think this: With this number of cases, Wuhan was already in lockdown.
With the number of cases in countries like the US, Spain, France, Iran, Germany, Japan or Switzerland, Wuhan was already in lockdown.
And if you’re telling yourself: “
Well, Hubei is just one region”, let me remind you that it has nearly 60 million people, bigger than Spain and about the size of France.