Pathogens, whether natural or artificial, have a fairly well-defined attack surface; the hosts’ bodies. Human bodies are pretty much static targets, are the subject of massive research effort, have undergone eons of adaptation to be more or less defensible, and our ability to fight pathogens is increasingly well understood.
It’s certainly not true. Pathogen can target agriculture or ecosystems.
I don’t remember the exact proof but shouldn’t be efficient algorithm to be an equivalent to solution of complete problem in #P/PP classes?