Mathematical models can confound many among us. Yet over the past few months, caught as we have been in a global predicament called COVID-19, we have been craving for theories and models that could rationally explain all that is going on around us.
There is no dearth of such models in Adam Kucharski’s book The Rules of Contagion (Profile Books, distributed here by Hachette India).
Kucharski, 34, an epidemiologist, is an associate professor and Sir Henry Dale Fellow at the London School of Hygiene & Tropical Medicine; his line of work involves mathematical analysis of infectious disease outbreaks. Kucharski’s book is academic and it does not cover the current pandemic (it was published just ahead of lockdown). What it lacks in drama, The Rules of Contagion more than makes up for it in terms of insight about a pandemic from its zero point, often delving into history to offer micro and macro perspectives of various outbreaks throughout modern civilisation, and the network such outbreaks depend on to spread at a global level.
Intriguingly, infectious diseases are not the only thing Kucharski qualifies as a ‘contagion’. He links the way a pathogen spreads to the 2008 global recession, the problem of gun violence, and even viral trends on the Internet. “I think we need to think of the processes of [a contagion] in terms of how they spread through a society and networks rather than just as these theoretical notions,” he says. Edited excerpts from an interview:
Is it now possible to draw a mechanistic model for COVID-19, considering the virus’ impact has varied depending on geography and demography?
There are aspects of COVID-19 that we can now capture with mechanistic models. In particular, there is a lot more information about the transmission, variation [of infection] at the individual level and the sort of interactions that might drive outbreaks. However, there are questions still about what exactly happened in different populations and why, for example, we are seeing larger outbreaks in some places than others globally.
You write that the media likes to portray someone as an ‘antagonist’ and pin a contagion on them. With COVID-19, there was no patient zero as such but a community was still made out to be scapegoats...
There have been examples in this outbreak where certain individuals were identified. When there were headlines about superspreaders, this kind of effect was noticed in [South] Korea when there was an outbreak in LGBT bars.
Cover of ‘The Rules of Contagion’
Subsequently, there was reluctance among some people to come forward and get tested because they didn’t want to be linked with the outbreak and potential stigma.
In many ways, the focus early on was on Asia; the threat was seen as coming from there and a lot of countries directed stigma in that direction, particularly the US even when there was ongoing transmission domestically.
Focussing on a single country or region after the outbreak may well have affected another country’s ability to respond domestically.
Not having a scientific temper among leadership groups can severely dent a nation’s response to an outbreak. Your thoughts?
Whenever we are dealing with an outbreak, science and modelling is obviously one part of the response, but there is also the question of how any strategy or approach can be implemented and the political will to do so. Mathematical models can be very useful for laying out the different scenarios we might see, and what will happen if control measures aren’t imposed. But it very much depends on the Government and its priorities as to what happens next. Many countries are balancing the models against other social and economic considerations.
You speak of ‘complex contagions’ in your book. Is the Black Lives Matter movement one such?
We see political movements spread in slightly different ways to certain other content online. A complex contagion is one where it might take multiple people and friends to adopt a belief before eventually it spreads to you as well. It changes the dynamics of how something spreads, because unless you have quite a lot of clustering or repeat exposures, it makes an idea much harder to take off. That is why messaging and attitudes around diseases, particularly control measures, haven’t spread necessarily as effectively as the disease itself because the disease only needs one link to spread whereas attitudes might need multiple links.
The rapid growth of Black Lives Matter is an example where political content reaches its critical mass faster. With BLM, what we need to understand is what helps messages get out there and, in some cases, what hinders them.
The use of ‘contagion’ to describe many crises makes the word sound less threatening or triggering...
One of my hopes with the book was to highlight that a number of different forms of contagion have these similarities, and have these underlying rules that we can understand. People view contagion as quite an abstract concept but ultimately whether we are talking about an idea or infection, it is going to be a social process, and it is not this distant threat or opportunity. It is going to be something that is really driven by people we interact with, often the people we are close to.
Is fake news a modern-day contagion?
There is a lot of evidence in face-to-face conversations that people who have a pretty strong pre-existing opinion may be harder to persuade to change their view. It depends on how the argument is made. If there is a very strong case, they may shift their opinion.
Interactions with fake news happens over social networks and online, where the debates often descend into fragmentation and polarisation. With disinformation, people actively try and manipulate the process to undermine confidence in the notion of truth. Blurring the entire argument makes it very hard for people to engage at all. This feature also makes fake news contagious. It means that fake news has the transmission advantage over correct information.
