One of the things that Bill Gates mentions in his recent TED talk about the coronavirus is that we need to be aware of what might be coming in developing countries, particularly in the southern hemisphere with winter about to arrive. (There's some evidence of a relationship with temperature.)

So far, countries like Brazil have been criticized for taking a laid-back approach to fighting the coronavirus. But the same could be said for many, or perhaps most, countries around the world at the outset.

However, in the case of densely populated slums -- like Brazil’s favelas -- the problem is expected to be more severe. Without the ability to socially isolate and without proper services, it is questionable whether they will be able to "flatten the curve" in the same way that some developed countries have. There's also a lack of government oversight in these communities.

Incidentally, the Financial Times is reporting that organized crime has started to step in to fill this void -- and it is happening over WhatsApp. Here is an excerpt from the above article: “Whoever is caught on the street will learn how to respect the measure. We want the best for the population. If the government is unable to manage, organised crime resolves,” read one message sent to residents of a Rio de Janeiro slum.

One hope is that rich countries will be largely through their outbreaks by the summer and that a vaccine will be well on its way.

(On a related note, here is an excellent slide deck from the London Business School on the economics of this pandemic. It's very comprehensive and worth a read.)

The Financial Times has some of the best charts/graphics that I have seen on the coronavirus and its impact. They're also free and regularly updated. Below is the cumulative number of deaths, by number of days since the 10th death (last updated March 23 at 21:00 GMT). I prefer this to the number of cases because it is more precise, though impacted by things like demographics. The number of cases is impacted by how good you are at testing. Some countries have been far better than others. And what we are continuing to learn is that lots of people were and are completely asymptomatic.

Seeing China (and Iran?) continue to flatten out is encouraging. (Note the logarithmic scale.)

Here has been the impact to the Chinese economy. It's slowing coming back.

And here are traffic volumes around the world. This chart was published on Sunday, March 22. At that time, Tokyo looked to be largely business as usual.

The Financial Times published the following chart last night. It shows the cumulative number of COVID-19 cases around the world, across the number of days since the 100th case in that particular country. The message here is that most western countries appear to be on a similar trajectory. (The grey dotted line represents a 33% daily increase.) Whereas in Asia, and in particular Hong Kong and Singapore, they have seemingly managed to slow the spread.

Now, there are a number of possible explanations for the outliers; everything from stricter quarantine rules to more rigorous testing. There's also an argument that Hong Kong and Singapore were better prepared as a result of the SARS outbreak in 2002. (More on these explanations, here.) But the other factor at play seems to be climate.

A recent study (by Jingyuan Wang, Ke Tang, Kai Feng, and Weifeng Lv) has concluded that, like the flu, the transmission of COVID-19 appears to be significantly impacted by both air temperature and relative humidity. In their research, they looked at the reproductive number (R), or the severity of infectiousness, for all Chinese cities with more than 40 cases between January 21 to 23, 2020. (Large-scale government interventions began on January 24, 2020 and would have therefore skewed the numbers.)

What they found was that for every one degree Celsius increase in temperature and every one degree Celsius increase in relative humidity, the reproductive numbers drop by 0.0383 and 0.0224, respectively. Air temperature, in other words, has more of a positive impact on containing spread than relative humidity -- which feels right. That is also apparent when you look at the above charts. Take note of Korea, Iran, and Italy near the top left corner of the temperature chart.

If you'd like to download a full copy of the research paper, click here.