Not to be a real downer on this book, but it feels like there's a lot of filler. You go through pages of unnecessary wordage to portray a simple thing. A bit more concise and tighter plot would help I think. Otherwise, it's ok. I've read worse Buffy novels and I still want to finish it, so that's something.
These chapters didn't feel like they moved on much with the story, except for the personal connection of Xander becoming infected. Xander being the victim has been done on the show before so that felt familiar.