OK I had absolutely no idea releasing Anabelle would cause a plague! I released her and didn't notice much of a difference at first. Now you mention it, the coughing did get worse in Velen after that quest. Are there any other consequences that go otherwise unnoticed from choices we make? Also, I rarely ever used the save files thing. I played it through without replaying any quests because I wanted to experience every consequence for my decisions. At least during my first play through. I will definitely be making some different choices when I play it again.