To be honest, I don't even think it is about eugenics, I think that is a brief plot device to set up the rest of the movie. I see it more as being about blind corporatism, humans having unlimited faith in legal entities that only serve profit, and don't serve their interests at all. Brawdo has electrolytes, it's what plants crave, even though it is clearly killing plants, people blindly trust the authority of a corporation and the government that is backing it. The Vaccine has mRNA technology, it's what keeps you safe and protected... The movie is mostly about being the only sane man in an insane world...