In the movie "I Am Legend," loosely based on Richard Matheson's 1954 novel, a re-engineered measles virus turns people into zombies.
Apparently posts claiming that vaccines turned "I Am Legend" characters into zombies have circulated widely , according to Reuters, which reported that people that the coronavirus vaccine prompted the posts.
Anti-vaccination misinformation-mavens apparently believe--or pretend to believe--that the movie was a sort of warning that vaccines could cause nightmarish side effects. Some, indeed, have said vaccines cause "zombieism" and even claimed that the US government was deliberately using the vaccine to create mind controlled slaves. Of course there's no way to make a vaccine do that. And by the way, the movie says nothing about vaccines; it only mentions a virus as the cause of zombieism.
And then there's another consideration. The movie is fiction. The screenwriters said their screenplay was based on an old science-fiction novel. No fact whatever. No allegory. No hidden message.
But the misinformation-mavens don't care. Their purpose is to spread fear, and hysterical anti-science clickbait. It doesn't matter to them how ludicrous it is. They know that the attention-span-challenged people thronging much of the internet won't take time to think it through. All that matters to the anti-vax liars is that they get their clicks, which helps them sell ads at websites; they even get donations. They prey on the stupid.
Sadly, preying on stupid people is a long-standing American tradition.