The Rules of Contagion” is available in the UK, not the United States. Although it is easy to get from Amazon in the UK. I read about it in the Economist in their April 4th edition; It sounded too timely to wait until September to read it, so I bought the p-book from Amazon.co.uk. (Update: Looking on Amazon.com, I see the updated publishing date in the U.S. was July 7 and you can now get it). It looks as if it’s been updated for Covid-19, but largely in the context of the existing material, which really tells you what you need to know to think about the mathematics of its threat, how herd immunity works, and so on. That’s good and was a source of comfort I got out of reading this in April — we’ve been here before, and just need to apply what we have learned in the last 100 years carefully to bring the spread down while we develop the right preventative measures and treatments.
The Economist review of the book is summarized as:
“Today, the freedoms and daily routines of many countries are held in the hands of epidemiologists. Amid the pandemic, these mathematical modelers have supplied scenarios for how travel bans, social distancing or stay-at-home policies could alter the trajectory of covid-19. This book charts the history of this now-pivotal science, from its origins in understanding the spread of malaria at the turn of the 20th century, to its central role in predicting the dissemination of everything from diseases to fake news in the 21st.”.
Adam Kucharski is an associate professor at the London School of Hygiene and Tropical Medicine. Given this, I was hoping to read about the common mathematical underpinnings of what Ronald Ross author of the 1910 book “The Prevention of Malaria” termed a “theory of happenings”.
Ross intuited that the characteristics of the malaria spread he analyzed could also be applicable to other things that happen over time.
He said, “in my own opinion my principle work has been to establish the general laws of pandemics”. As Kucharski then says, “he didn’t just mean disease epidemics”.
So, the book contains great examples of non-disease epidemics and the similarities between them in terms of how susceptible, susceptibility, infection, and recovery occur in “happenings” such as:
- disease contagions
- the spread of ideas (sometimes referred to as memetics)
- the diffusion and adoption of technology
- “viral” marketing campaigns
I found the material on pandemics to be good, though lightweight background for the deeper reading I have been doing since February of academic research papers about COVID-19. But I learned more from these research papers then the book about this topic.
In addition, I had already read better books about the spread of ideas:
- “Thought Contagion” by Aaron Lynch
- “The New Science of the Meme” by Richard Brodie (MSFT employee #77, by the way)
- “The Selfish Gene” by Richard Dawkins
- “Linked” by Albert-Laszlo Barabasi
The book gives a great overview of epidemic theory which we’re all interested in these days. You have probably heard about the reproduction number otherwise known as R0 — pronounced “R-naught”. Kucharski says: “(R0) asks: How many people would we expect the case to pass the infection on to?” He compares R0 for pandemic flu, Ebola, HIV, smallpox, and measles. We also learned that R0 depends on four factors:
- The duration of time a person is infectious.
- The number of opportunities — on average, that an infections person has daily while they are infectious.
- Transmission probability of 2).
- The average susceptibility of a population.
and how each of these four variables can be traded off against each other to produce R0. Here is the equation given to illustrate this:
R₀ = Duration x Opportunities x Transmission probability x Susceptibility.
He uses the mnemonic “DOTS” to refer to these four factors and makes it clear that all conversations about how to deal with viruses must refer to each of these elements to be intellectually valid.
We also see these variables defined for and applied to the viral spread of Internet posts and gun violence. Seeing the parallel applicability of these concepts towards the major events we are experiencing now will give you a good framework for thinking about and evaluating proposed solutions to many of our culture’s current challenges.
As I said, I was hoping to learn more about the mathematics of these applications than Kucharski presents here. Nevertheless, “The Rules of Contagion” is still a good book for people who want an introduction to concepts underlying contagions. It is obviously a great thing to get some grounding in today.
Most readers will find that the intellectual coverage gained from reading this book around these topics more reassuring than frightening. You will better understand what needs to be done during the current pandemic and be personally equipped to judge our leaders are handling COVID-19 for yourself.
5 stars — I cannot recommend this book highly enough.
