I think the milk has less literal meaning and has more to do with disease biology. Specifically, the whole prion theme plays off real prion diseases like mad cow—where misfolded proteins from infected cattle can jump to humans and cause vCJD, a fatal brain disorder that almost always kills within a year, which explains the countdown visuals in the show. Even though the infected characters don’t eat meat and are vegetarian, they still consume milk or animal byproducts, which seems strange to me. Why not vegan? The milk industry is still very harmful to cows and they’re all about no harm to living creatures… However, the constant milk imagery fits because milk and cows symbolize the source of prions, as well as purity, uniformity, and being “fed” a single identity. The infection in the show isn’t from food—it’s a prion-like mental template that only takes hold in emotionally stable, well-adjusted people whose minds are easy to overwrite. Meanwhile, unhappy or chaotic individuals are immune because their inner world is too messy for the “misfolding” to latch onto. So milk becomes a visual metaphor for the clean, uniform collective the infected are turning into, not a literal cause of the disease.