Hollywood has churned out dozens of zombie apocalypse movies over the last few decades. Now a group of undergraduate researchers in the UK have applied science to figure out how fast a zombie virus could spread through the human population. The study was part of a series of tests involving the application of science to real-world or hypothetical scenarios.

Zombie epidemic kill humanity
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Analyzing the impact of zombie apocalypse

Findings of the study were published in the Journal of Physics Special Topics. This is not the first time scientists have used zombies as a public health metaphor. In 2015, the popular journal The Lancet had published a research paper warning of the walking dead. Another study had analyzed the best places to hide if a zombie apocalypse happens in the real world.

Undergraduate researchers at the University of Leicester in the UK used the SIR model, which is widely used in medical sciences, to determine how fast the zombie virus could spread through the population and possibly wipe out humanity. They split the population into three categories: people susceptible to infection, those that have been infected, and those that have died or recovered.

Only 181 humans would be left in 100 days

Then researchers looked at how quickly the infection spreads and the rate of death due to the virus. For the study, they assumed that each flesh-eating monster would have 90% success in finding and infecting one human per day. At that success rate, the zombie virus would be twice as contagious than the Black Death that claimed millions of lives in Europe in the 1300s, reports Live Science.

They further assumed that a zombie could live up to 20 days without brains. The epidemic would spread so fast that the human population would decline from approximately 7.5 billion to just 181 within 100 days. And there would be 190 million zombies roaming around on the planet. For the study, they assumed that there is no geographical isolation.

There is still hope for humanity

In case of limited geographical isolation, the human population would be 273 at the end of 100 days. Not a bright scenario. However, scientists added that they did not take into consideration natural birth and death during the epidemic. Natural death rate would be “negligible” compared to the rate of infection if such an apocalypse happens. They assumed that, over time, humans would become less likely to be infected by zombies as they get used to the threats and prepare themselves to deal with them.

In a follow-up paper, researchers assumed that each human would have 10% success rate in killing at least one zombie per day. Accounting for this and other factors such as human reproduction, they estimated that the human population would decline to just a few hundred. Fortunately, the zombies would die off or get killed after 1,000 days, and human population would start rising after 10,000 days.