Rappler Talk: The exponential growth of a pandemic

Rappler Talk: The exponential growth of a pandemic
Tomas Pueyo, the author of the Medium article 'Coronavirus: Why You Must Act Now,' talks about the lessons he learned from data and what nations should do next


MANILA, Philippines – Rappler’s Maria Ressa talks to Silicon Valley entrepreneur and behavioral psychologist Tomas Pueyo about his Medium post “Coronavirus: Why You Must Act Now” which was read by tens of millions of people around the world.

In this interview, he talks about the lessons he learned from data, including what’s really happening behind the scenes of the numbers reported in each country around the world as they report contagion.

He explains what happened in Hubei, China – the difference between the numbers reported and the greater number of people infected but not yet detected. This is happening all around the world today. 

 Chart republished with permission from Tomas Pueyo

Pueyo focuses on how nations and leaders should manage this threat: that the goal is linked to each nation’s capacity for intensive care and the number of ventilators it has available. He shows this through the wide difference in fatality rates between Singapore (which has no deaths), South Korea at 0.6%, and Italy at 4-5%. 

NOTE: In his analysis of the exponential growth of the contagion of COVID-19, Pueyo compares data from many countries around the world. Epidemics normally follow growth curves called a “sigmoid.” To get that though, the crucial inputs are how, why, and when the exponential curve will switch to a log phase. We haven’t reached that stage yet in most countries around the world, including in the Philippines. 


MR: Tomas, thank you so much for joining us here in Rappler. You wrote this Medium post about why we should be acting – looking at the data all around the world. It has gotten tens of millions of views around the world. Why did you do this and what did you find?

TP: Why? It just happened. I started seeing the news around a month ago, like everybody else. I looked into it, and what I saw was exponential growth. And my job is in exponential growth – in creating it, identifying it, and pushing it. So as soon as I saw it, I understood what the potential was. And so I started posting on Facebook a couple of articles about it. And I realized two things.

The first thing is people wanted to know more about it, because they didn’t know much. And two, most people were not realizing how bad the problem was. And so it’s interesting. I could see it coming weeks in advance and I was seeing people not reacting to it. So every day I would post more and more, and more people would come, start following me, start following the advice, saying they wanted to hear more. And at some point, two weeks in, somebody said, “Hey, what you’re writing makes a lot of sense. I need this packaged to send to a group of friends.” So I basically put everything I had on Facebook, properly structured, on Medium. And that’s it. I expected maybe 10,000-50,000 views. My most viral post before had around 250,000 views, so at most something like this. I was definitely not prepared for tens of millions of views.

MR: From the countries that you looked at, looking at exponential growth, I think the hardest thing is for normal people to understand what exponential growth means. How did you explain it?

TP: I think one of the best ways to look at it is with the graphs and comparisons. People had a good understanding of what had happened with China. So every time you compared reality with what happened in China, people really paid attention. One of the examples is, Wuhan ordered a lockdown when they had around 500 official cases. And even last week, when I wrote this, there was a bunch of countries that were past that level, and they were not doing anything. That really caught people’s attention because they realized, “Oh wow, Wuhan had thousands of dead because of this, and we are past that level and we haven’t done anything. That was one of the big ones. The other was, as I mentioned, the graphs. Everybody knew Italy and Iran were going like this. And everybody thought, “It’s just these countries, they’ve mismanaged it. We’re fine.”

But if you zoomed into the small little countries that were not very big yet, you could see it was exponential for everybody. And from there, it’s going to be easy to know what’s going to happen in the next few weeks. If you have 100 cases and you’re growing exponentially – if you don’t do anything – at some point you’re going to be worse than China.

MR: I thought what was interesting about what you did is not only did you show the exponential growth and that it could be worse than China, but you also tackled things like, “Here are the reported numbers but what wasn’t reported is actually far more significant.” You showed it in China’s case, in Wuhan’s case. I guess can you explain that as well?

TP: That’s right. There’s 2 ways in which the official cases don’t correspond to the true cases. The first one is testing. You have countries like South Korea that are testing everybody, and they’re uncovering a lot of cases. But most of the other countries aren’t. So how are you supposed to know the number of true cases when you only have the official ones? So I used a couple of ways to approximate that. One of them was with the number of deaths, because you can tell how many deaths there are because of coronavirus. This is because usually if you think a death might have been caused by it, you’re going to test. So you know the deaths. And there’s an approximate ratio between the deaths and the cases. And the way it works is, if you died today, you were probably infected 3 weeks ago. But let’s say that the fatality rate is just 1%. So 3 weeks ago, there were 100 people infected, and only 1 of them died 3 weeks later. So these 100 cases that existed 3 weeks ago, these cases are doubling approximately on average every week. So it doubled 3 times. So 100 cases 3 weeks ago, means 800 cases today. And 1 death as a rule of thumb means 800 cases. And that was not in the official numbers. So that’s one of the ways.

The other way, the one you were referring to is… by the time you come to the doctor, you already have symptoms. You are already sick. But that’s not when you became infected. The graph that was beautiful about Wuhan is this difference between the official cases and the true cases. These true cases, the way they assessed them was – looking backwards. Every time they had somebody come in and get diagnosed, they asked when they started having the symptoms. Thanks to that, you can get two curves. You get the curve for the true cases and the one for official cases. And you can see the official cases are two weeks later than the true cases. If you made a comparison with people in other countries, you’re saying, “Look, you have 500 cases right now. But you have substantially more, you’re just not seeing it because people just got infected and they don’t even have the symptoms yet.”

MR: You also talk about what governments should be managing for – that in the end it goes down to the healthcare facilities. Can you tell us more about that?

TP: Yeah. A lot has been said about the fatality rates of the coronavirus. If you catch it, will you die, basically? And the range is very big. It goes from around 0.5% to 5%. So that’s a 10 times difference. 0.5% is still bad – it’s around 4 times worse than the flu. But 0.5% is much better than 5%. So what is causing the difference between the two? What we’re seeing is, we can tell the difference based on different regions.

For example, in China, in the region of Hubei, the healthcare system was completely overwhelmed. They couldn’t handle everybody. Specifically, they could not properly handle the people who needed intensive care. They needed ventilators because their lungs didn’t work anymore, and without those ventilators and other machines, these people would die. And when your healthcare system is overwhelmed and you don’t have enough of these, people die. Compare the fatality rate in Hubei which is 5%, to outside of Hubei, which is around 0.9%. Why? Because in these other areas, the systems are not overwhelmed. And then the same thing happened with South Korea on one side, and Italy on the other side. Nearly identical situations, but you have a fatality rate in South Korea of around 0.6%, and in Italy, it’s closer to 4-5%. Same thing – they didn’t get overwhelmed in South Korea and they did get overwhelmed in Italy.

And so the point is, the number one goal here is not actually that nobody has it, because that’s hard. We should try, but that’s not the number one goal. The number one goal is not to overwhelm the healthcare system.

MR: That makes sense. I had covered SARS in 2002-2003 out of Singapore, and then post-SARS, I looked at how they codified the lessons they learned in their system. And this is part of what they’re doing right. What they said today is there’s a tripod that every government is going to have to deal with. The tripod is the quality of the healthcare system of each country, the quality of governance, and then the last part is social cohesion. I believe you also wrote this in your piece – 3 countries to look at are Singapore, Hong Kong, and Taiwan. All these 3 dealt with the SARS virus, and they moved relatively proactively on it. Singapore still does not have a death [from COVID-19].

TP: Incredibly. They have more than 200 cases, and not a single death.

MR: And I think that aligns exactly with what you said. The managers of Singapore have actually stated that they’re managing for ventilators, for healthcare capacity, for intensive care capacity. What advice would you give governments and leaders today?

TP: Buy yourself time. Most countries in the world are just overwhelmed, not just in the healthcare system, but in the political system. Because unlike Taiwan, Singapore, Hong Kong, Japan, and South Korea that went through this, they haven’t. They don’t understand what exponential growth is, and they don’t understand all the consequences that are going to happen. And so you have this combination of a world full of unknowns, and a threat that’s coming at you at an accelerated speed. The most valuable thing you can do right now is give yourself time – enough time to react to it.

It means that I believe countries that have a fair amount of cases should be as aggressive as the society can tolerate. Why? Because of many reasons. Number one, of course the number of cases and transmissions goes down. The healthcare system gets relief. It gives you time to do proper testing, so you understand the magnitude of the problem. It gives you time to build capacity in the system. More ICU beds, more ventilators, more masks, all these things. It gives you time to increase the production of all these things. It gives you time to understand the different measures you can then take, and what is the cost and benefit of each one of them – how much each measure reduces the transition rate, and how much it costs socially. Because right now, they have thousands of potential measures and they don’t know which ones to pick. And it’s very hard because these different measures have different costs. There’s many more reasons to act immediately, and hard. It slows down everything. It gives you time to think. It gives you a few weeks in which you can then have a more intelligent approach for the long term.

MR: That’s fantastic and that’s part of what was very clear in what you wrote, Tomas. Your job is to look at growth though, right? So you’ve looked at the growth of the contagion, and you’ve come up with excellent suggestions of what government should be doing. The last question I have is more that this is global. It’s the first time we’ve seen a pandemic like this. You understand business, you understand growth of business, and the kind of breaks that this is going to do globally. What do you see happening with trade, the economies?

TP: This is a fascinating question. I think there’s a short term and a medium term. In the short term, everything is going to suffer. There was an interesting piece by Ray Dalio, the founder of Bridgewater, who explained the different pandemics of the 20th century and showed what the impacts were on the market. And one of the key takeaways there is that pandemics like this are just a dip. So if you have the economy and the market’s going [up], it goes a little bit down, and then back up. If you eliminate this little hole, it’s as if it had never existed.

It is likely that something like that is going to happen from the market’s perspective, exactly what I hope. But if you think about it, it’s very likely that in a few months we might have a treatment, in maybe weeks. After that, there’s going to be a vaccine and things will be able to go back to pre-normal, depending on how much this thing mutates. But I think the more interesting question actually is, what’s going to happen in the long term? I think this shows the emergence of 2 trends at the same time. Number one is the value of decentralization and free speech. The reason this wasn’t caught earlier in China is because of decentralization and the lack of free speech. If you enable everybody to raise their voice, and you listen to their voices, that is a very strong way to prevent this kind of thing. So at the lowest level – empowering the individual is a trend I think this is going to push towards.

And then at the exact opposite of the chain, at the supranational level, you have a situation where the WHO was on top of all of these things. They understood exactly what was happening. They understood exactly what they needed to do. And they had zero power. And so you’re getting to a world where now the actions of one country are going to be impacting what happens in another country. That requires a very strong debate about what are the right levels of authority for different needs. So for example, I can imagine a world where WHO was given more powers than it has had in the past, because it could have a substantially better reaction than any government standing alone.

MR: That’s interesting. Just as a corollary to something you said earlier – the free speech vs. centralized speech. Draconian measures work the best in this time and age. And ironically, it’s the West – which hasn’t been used to taking these kinds of things – where the spread has taken off exponentially. What kind of impact do you think this will have on democracies?

TP: Japan is a democracy. Taiwan is a democracy. Hong Kong is fighting hard to be a democracy. To me, it’s more a matter of training than it is of democracy. If the Western countries had been more experienced, they would have had a better reaction. I think it’s also a sign of the political class. I think many times they want to react to what people think, rather than show leadership. To me, this is a perfect example of a moment when you can show leadership. Like when I hear for example, something like the UK government said, “Oh, we’re not sure that people are going to keep this behavior of being locked down for months, so we don’t want to coordinate right now.” It is your responsibility to make that happen. Show some leadership. So I definitely don’t see it at all as a failure of democracy. Of course an authoritarian regime can coordinate things substantially faster. But democratic governments also have the mechanisms to do it. For example, now with a national emergency, there’s plenty of powers that he can have to do whatever he wants very, very fast. I was in a conversation with a group earlier today that was saying, “Hey, can I sue the American government because they closed my church?” The answer is absolutely not. Not only that, but if you’re outside and there’s a curfew, they can take you and they can lock you up and there’s nothing you can do. And so the democracies have the powers to do it. I think what we’re lacking is just the experience, and in some cases, the leadership.

MR: OK. I know I said last question, but this really is my last question. This is a new time, you said this earlier. New powers for WHO. On everything, we’ve never lived through anything like this, just the same way tech brought along a situation where we’ve never lived through anything like that. Social cohesion, trust, there’s so many different factors to include into this. I guess if you were to pull out one lesson, one factor, that countries, societies all around the world need to keep in mind, what would that be?

TP: It’s a very interesting question. I think the key is, people don’t incorporate information easily. Our brains are structured in a way that we learn from the world, especially when we’re younger, we understand how it works. And the older you get, everything is stable, and you don’t revisit it. Come something like this, there are many things you need to revisit, but you’re anchored in your previous way of thinking. The human brain is not well-structured to incorporate this new information. And so that is, to me, why people haven’t reacted completely. They just couldn’t grasp how big the change was going to be.

This epidemic is going to create several changes culturally. Some of these, you have already seen in countries touched by SARS. For example, I’m going to guess it will be completely unacceptable to cough in public without a mask. Not acceptable to go to work coughing, where in the past, in some of the countries where I worked, if you just had a cough and went home, it’s like, “What? Are you lazy?” Maybe the handshake is done. Definitely, people are going to wash their hands more. And so some of these changes are going to stay with us over the next generations.

But to me, the more interesting concept is that one of incorporating new information. The more globalized and connected the world is, the faster it goes, the faster it progresses. The faster these changes are going to be coming. And we will need to adapt our way of being to be able to incorporate this new information as fast as we can, to change our models of how the world works as fast as we can.

MR: Tomas, thank you so much.

– Rappler.com

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