Why change the ending of Inferno from the novel?

Question

** SPOILER warning for anyone who has not watched the movie or read the book **

In the novel, at the end, it is revealed that the virus was never meant to kill anyone, but instead made a part of the world's population infertile, which is quite a good ending in my opinion. It provides a solution to the problem of over population, while not killing anyone. There couldn't have been a better ending. Also actually releasing the virus way before the alleged time made a lot of sense and the fact that almost everyone has the virus at the end provides a sort of meaningful conclusion.

In the movie, the virus was in fact going to kill a lot of people and paints Zobrist as a terrorist. Also the ending seems incomplete as the problem still stands at the end, earth is still doomed.

So why would they change such a good ending and replace it with a much poorer one? Did the idea of a part of population infertile seemed a little controversial to the Studio?

Answer 1

In a nutshell, the ending in the book was too drawn out and "wasn't cinematic" in terms of keeping the audience engaged.

According to an interview with director Ron Howard:

"My recollection is, Langdon wasn't really actively involved," Howard told us. "It was so complicated and not really movie-ish. He got [to Istanbul] and it had already been released. And so now, the upshot was, well, half the population has this thing, and we don't quite know who has it, and we don't know what's going to happen. [Sienna Brooks] kind of runs away and Langdon chases her down and says, 'How could you have done this?' And then he convinces Sinskey [head of the World Health Organisation] to hire her to help seek an antidote. The kicker is, not everyone's going to die; it's not instant death, it's a fertility plague. And so, interesting, and intellectually intriguing, and we missed it on that level. But it's very drawn out, and I can imagine staging those scenes and a movie audience sitting and kind of saying, 'How many endings are we going to have?'"

The decision was therefore made to come up with a more explosive conclusion - one that would require less exposition while giving Langdon more to do. "The feeling was, that ending worked great for a novel, but the complexity of it required a tremendous amount of explanation. I think I felt like that was something we got bogged down with a little bit in the previous movies, and when we found a way of narrowing the focus of the third act, it felt more satisfying on a movie level."

The author of the novel, Dan brown, was also apparently on-board with the change, and summed it up quite succinctly in an interview:

Anytime you're going to adapt a novel into a movie, a movie that is not 25 hours long, some things are going to have to be simplified. I know that the novel had a subtle, ambiguous ending. This was much more direct, right to the point of it.