By: David A Fein, MD
Think those Zombie Apocalypse movies aren’t something to worry about? A medical study recently published in a peer reviewed medical journal has found that the entire human population of the Earth could be reduced to just a few hundred survivors in just about 100 days once the Apocalypse starts.
It would start slowly. The researchers found that if we start with a population of 7.5 billion people and just one single Zombie, it is going to take nearly 3 weeks before the epidemic becomes noticeable. But by that time, the damage would have been done and the Zombie pandemic would have been unleashed. Within weeks, there would be almost none of us left.
Of course, the researchers had to make certain assumptions about their Zombies to reach this conclusion. They estimated that each Zombie would live for about 20 days and would have a 90 percent success rate at infecting one human per day. That may not sound like a lot for an enterprising Zombie but it is about twice as efficient (and contagious) as the Black Death plaque that ravaged Europe in the 14th century.
Of course, as the Zombies succeeded in converting humans into more Zombies there would be fewer and fewer humans remaining for them to infect. And, it is unlikely that we would all just take this lying down. Sooner or later, we would have to find some way to kill the Zombies.
So, in a follow-up paper, the researchers took that into account. They gave each remaining human a 10% chance of killing one Zombie per day. They also added in an assumption that each woman of child-bearing age would have a baby every three years to try to repopulate the Earth. But they also extended the Zombie lifespan to one year.
Under that scenario, the human population still drops to just a few hundred people pretty rapidly. However, after 1,000 days the Zombies have finally died off, too. It takes almost 30 years but eventually the human population begins to recover. So, if we can find a way to at least neutralize a few Zombies per day, humanity has a chance of surviving.
Is this likely to happen? Well, probably not with Zombies. But the study is a useful model of what could happen if a sufficiently lethal and contagious new virus appeared in the population. The researchers used a new mathematical model to simulate how a disease might spread over time through a large population. The use of Zombies makes it entertaining. But it is a worrisome warning of how devastating an epidemic of a super-contagious and lethal strain of Ebola, Smallpox, Influenza or some new virus could be before we can start to produce a vaccine or drug or even know that they infection has taken hold.
In an age where new genetic editing technologies such as CRISPR-CAS9 can make the ability to create customized new viruses readily available even to individuals without access to high tech laboratories, a Zombie Apocalypse may become one of the least of our worries.