The minor question is, what are spared denizens supposed to do during 4? Fumigating a building requires it to be evacuated, and I’d certainly like to know where 521 expects New York City’s remnant populace to spend fumigation time.
Actually, you also need to seal the building so the poisons don’t seep out. How do you do that with a city?!
Where does this sort of bloodlust come from, anyway? I’m less than convinced the stereotype of sexual strands is accurate.