I don't remember the movie terribly well either, but it was much more chaotic. And at best, there isn't really a lot of time for back story in a 2-hour movie compared to a series that plods along for 4 seasons very earnestly trying to establish a coherent universe.

What struck me about the underlying assumptions was not so much the rate of mutation, but the idea that it would take 20 years to create a vaccine for a novel virus. And that even after 20 more years of research it would be such an insuperable obstacle to adapt the vaccine to a new variant.