You don't always have to look to the real world to figure out how plagues propagate.
Scientists in Finland are modeling a very (hopefully at least) fictional scenario to help understand how pathogens spread. Specifically, they're looking at the shambling undead – the ghoulish risen with a taste for human brains – zombies.
This effort, which focuses on individual interactions instead of a population-wide model, could reveal insights that aid in the preparation for future pandemics, the researchers say.
A team led by mathematician Pauliina Ilmonen of Aalto University has been conducting models of a zombie uprising, altering the parameters to determine how a plague of undead would unfold across Finland. Although the full results are yet to be published, the simulations are already ponying up some insights.
For example, the window of time for containing a zombie outbreak is very narrow; with just a single zombie in Helsinki, we'd need to act within just seven hours by destroying the 'infected' agent or quarantining the city. After that, zombies overrunning the entire country is inevitable, the researchers say.
"I shouldn't have found it surprising, but I was surprised at how quickly we have to react to keep our population alive," Ilmonen says. "It made me think about moral issues like the rights of individuals versus the rights of a population."
Using fictional scenarios to understand how plagues propagate is not a brand new idea. Zombies have been used to engage medical students in epidemiology studies, for instance, as well as other disciplines, such as mathematics. Even the CDC invoked zombies in 2011 for a public pandemic preparedness campaign.
A bug that spread through multiplayer game World of Warcraft in 2005, known as the Corrupted Blood incident, also gained global attention from epidemiologists for the way it seemed to model real-world pandemic propagation. It hinted at the power of simulation to model the spread of infectious disease. Even the simulation video game Plague Inc. has been used as a tool to study the COVID-19 pandemic.
But it's surprisingly tricky to design such a simulation that works in a realistic way.
"What's the right probability for a human winning an encounter with a zombie? The problem is that we're walking blind here, because real data on such questions is severely limited," says mathematician Lauri Viitasaari of Uppsala University.
Mathematician Natalia Vesselinova of Aalto University adds, "The large number of human-zombie interactions that have to be simulated makes this model computationally intensive." The solution was to simplify the model so that it could run on less power, while still giving realistic outcomes.
Now that the team has shown that their simulations work, they say it can be adapted for other regions of the world, and even other scenarios. For example, it could be used to study how rumors and gossip get around, or the spread of dangerous disinformation. In turn, this could help develop mitigation strategies, the researchers say.
It certainly seems like zombies are an underutilized resource in epidemiology. We'll be interested to see where this line of enquiry leads.