In Ron Howard’s Inferno, the third installment in the Dan Brown-inspired series of films, Robert Langdon (Tom Hanks) returns, once again, to save the world from imminent doom: Unlike in The Da Vinci Code or Angels and Demons, however, Langdon isn’t up against sinister Old World establishments like the Vatican or the Illuminati: This time, he’s facing off with a world-ending virus.

If it’s released, the unnamed pseudo-plague, which has been incubating in huge amounts under the gaze of an evil tech billionaire, will wipe out half of the world’s population, and Langdon races to beat the clock. As he observed this scenario play out on screen, Caltech biologist Alexei Aravin, Ph.D., scoffed at the Harvard symbologist’s urgency. A virus of such potency — with the ability to both infect and spread at such a rapid success rate — simply doesn’t exist in nature, and even if it could be genetically engineered, he says, it’d be impossible to predict its behavior. Here, he explained to Inverse why we have nothing to worry about.

How realistic is the scenario that plays out in Inferno?

In the movie, there’s not much information, actually, about this virus — what exactly it is, and how it’s produced. If it’s released, it will spread through water and kill a significant proportion of the world population. It’s something very dangerous.

How realistic is this? It’s not totally unrealistic, because obviously there are deadly viruses, right? With current technology, it’s potentially possible to maybe modify natural viruses to make them even more deadly.

So it is possible that genetic engineering can produce viruses that deadly?

It’s theoretically possible. But how practically can it be done? I think much less. First of all, in the movie, it’s this crazy billionaire that decides to do it. In reality, if somebody thought about doing something like this, it would require lots of people to be involved. Hopefully it would be difficult to find a lot of crazy people, right? Second — even more importantly — the reason why [reality] is less dangerous than it looks in the movie is that, even if somebody tried to modify a natural virus… you would try to do something, but really, how would it behave? You wouldn’t be able to say with any level of certainty unless you tested it.

What would make testing it so difficult?

In this case, testing it means you really have to test it on other people. In the movie, they try to release something, but they have no idea how it will really behave. Essentially, on one hand, it’s possible to think of something like this, but in reality, how to do it? There is not a high chance of creating something like this.

That’s encouraging.

People have obviously been thinking about biological weapons for a while. It’s not something that’s appearing first in this movie. But to my knowledge — maybe, of course, there’s some secret program, where somebody’s doing something — but to my knowledge, there is no real biological weapon that’s being pursued by any country. The reason is exactly the same. It’s not only difficult to do, it’s difficult to do it in a way that will be targeted to only your enemy and not to anybody else. In the movie, they actually don’t care.

In the movie, they’re just trying to reduce the world population, so they don’t try to direct it to any specific country. You need to test, and testing biological weapons is really impossible.

Is that because it would take a long time?

Not just a lot of time, but how would you test it? It involves killing people. You potentially can test it on animals, but viruses on animals don’t [always] behave the same as [those] that infect humans. It might infect some animals, but it will probably behave very differently — how it spreads, how it infects. You’re really very limited in observing its effects on animals. Obviously, humans you won’t be able to test.

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So we shouldn’t be worried this could happen in real life.

I don’t think people should be really worried. There is, obviously, some real science behind this: Viruses can be dangerous. There’s the recent one, Ebola.

We should be hiding from evil tech billionaires, not humanity-threatening superviruses.
We should be hiding from evil tech billionaires, not humanity-threatening superviruses.

Do any natural viruses behave like the one in the movie?

What’s described in the movie would actually be quite different from any natural virus we know of. It would have to be highly infectious — spread through water — and it would have to survive a long time. One of the most dangerous viruses we know is Ebola, but that also won’t spread very easily. If you tried to create something really dangerous, it would be [something like] the HIV virus, which you would modify to spread through air or water. But it’s not very easy to spot. If a virus kills a person right away, very fast, it actually cannot spread very easily from one person to another.

Why is that?

If the disease can be recognized very fast, you can isolate people and make sure it doesn’t spread. With HIV, the reason it is so dangerous is because it takes a long time to actually recognize the disease. It’s actually sort of invisible until it’s infected a lot of people. And then it will cause problems. Nothing like this really exists.

In other words, a virus of mass destruction would have to be effective at killing and spreading, which doesn’t happen naturally.

In the movie, they don’t describe how they create, again, this thing — whether they modify the natural virus or they create something from scratch. In reality, it’s impossible to create something from scratch. The only realistic way is to modify something already known.

Would it matter what medium you used — air, water, or direct transmission — to release the virus?

For a real virus, it matters a lot. There are obviously viruses that spread through aerosol, or those that are directly transmitted from human to human. For real viruses, [what matters is] how long it can survive and in what environment. Of natural viruses, there are very few that can survive a long time in water or air.

Are there any that come close?

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Influenza can be transmitted by air really easily. This is one of the natural viruses that is also potentially dangerous, and there have been very deadly influenza outbreaks in history.

Photos via Jonathan Prime, CTMG., Jonathan Prime/CTMG