The last ten months have been some of the most hectic our generation has experienced, with a public health catastrophe as an accelerator of change and tumult in our society. Misinformation has spread, protests for Black Lives Matter resulted in record turnout, and the coronavirus has mutated into a more contagious element that imperils more people daily. Adam Kucharski’s book, released in the middle of a pandemic, explains how contagion works and relates all of the themes above into a coherent narrative based on his near decade of work as a mathematician and epidemiologist.
This was a timely piece of work that would still be relevant even if we all weren’t socially distanced due to COVID-19. Kucharski is relatively young for a professor, and he neatly ties in his experience interning at an investment bank before the 2008 financial crisis to explain how the financial system’s interconnectedness was similar to a pandemic’s spread. By now, most of us have heard about the variable r, or reproduction number, but Kucharski goes into detail to explain how r is influenced by a dynamic list of factors: duration of a virus, opportunities for spread, the probability of transmission, and susceptibility to the infection, or DOTS for short. Any type of outbreak needs to be understood by these four different factors before action should be taken. For example, health agencies have focused on these factors in order to control HIV spread or smallpox.
The first half of the book was relatively heavy on math and goes into excruciating detail on the history of epidemiology from the late 1800s until today, all of which may not be relevant to the casual reader, but the latter half of the book was particularly enjoyable to read because of Kucharski’s ability to connect contagion to a number of different cases, from things going “viral” on the internet (while proposing an interesting case as to why marketing firms should understand disease modeling before launching campaigns) to how computer viruses spread (based on computer programmers reliance on copying and pasting other people’s codes over time). With most of us living in a time where we judge things as they happen and react accordingly, I find it reassuring that it is possible to understand how events like gun violence or stock market bubbles transpire through the lens of elegant mathematical analysis. For example, we can determine the size of an outbreak if we know its’ reproduction number in a formula that is transferable across a number of different functions: Outbreak size = 1/(1-r). However, the most interesting connection Kucharski made to disease modeling was his analysis of how folk tales originated. Using modern phylogenetic approaches, he takes the reader on a journey to explore the origins of “Little Red Riding Hood” and how its story has been adapted and mutated from a number of cultures over time.
I came away from this book impressed by its scholarliness and the breadth of material it covered over 266 pages. This is an excellent and timely resource for anyone trying to understand the mathematical significance behind all types of transmissible events and the future biostatistics holds across a number of industries.
Buy The Rules of Contagion here, or check it out from your local library.
