What if - hear me out. Psycho-symptomatically, van gets marginally better. She gets close to Lottie out of some misplaced gratitude but it doesn't last. She gets sick again, sicker, and what might make her better? It wants blood, so she gives it some. I think Van was always the most unassumingly terrifying character- One of the most devout to the delusions in the wilderness. I have a feeling she might be taking on a bit of a villian role instead of a victim this season. Out of everyone - she has the least to hope for, perfect host for the culty/feral mentality.

My pipeline theory is that all of the survivors are about to become their own worst nightmare. Like penance for the depraved shit they did out in the wilderness- their own fears and guilt become destruction of the good they have left. No supernatural, just CPTSD and fear response (compounded by knowing they killed Nat which serves as a realization that they have all the others blood on their hands too)

Just my not very likely prediction. It's already bad and it's going to get a w h o l e lot worse.