Wednesday, May 20, 2020

The Fascinating Story of the Oscillating Epidemic.

I was surprised, today, to find this graph on Google. What struck me was the evident periodicity in the number of deaths in the US. Most of the deaths take place on Thursdays and Fridays. On the contrary, the minima in the curve are almost always on Sundays. Why don't people die on Sundays?

It may well be just a case of bad reporting. I went on, exploring for more data and I discovered that there is something of a worldwide "beat" that generates a weekly periodicity in the deaths. Here are the data.  In this case, instead, people seem to like to die on Fridays and Saturdays, but they stay more alive on Tuesdays.

Some regions show clear oscillations, such as the Netherlands, as shown here. In the Netherlands, people die mostly on Wednesdays and survive best on Mondays.

Other countries, such as Italy, don't show a clear periodicity in the number of deaths

So, what can we conclude? Well, I think that the hypothesis that it is a reporting problem is the most likely, yet it is a little strange for various reasons. Possibly it is the bad quality of the data that messes things up

But there is another possibility that I have been considering: that the deaths caused by the coronavirus feel the weekly "beat" of the world activities. In other words, people have a weekly rhythm of working and moving around. It is a periodicity that is reflected in the number of social contacts, then reflected in the number of infections, and finally in the number of deaths. It is an internal "clock" of the system that's reflected on its overall behavior, just like the ice ages of the Pleistocene were clocked by the wobbles and the oscillations of Earth's orbit.

That would explain why the oscillations are clearly detectable in the US and in the Netherlands, where the government implemented a rather light lockdown, but not in Italy, where the lockdown was very strict. In Italy, people lost track of the day of the week -- no more working days, no more weekends. So, no periodicity that would be reflected by the coronavirus cases.

Maybe. More work to be done, more than I can do right now, and I think we need better data. But I thought I could propose this chain of thoughts to the readers of "Cassandra's Legacy" Maybe some readers have different and better ideas? In any case, we keep learning new things with this coronavirus!


Ugo Bardi is a member of the Club of Rome, faculty member of the University of Florence, and the author of "Extracted" (Chelsea Green 2014), "The Seneca Effect" (Springer 2017), and Before the Collapse (Springer 2019)