No idea but the horse has to be without food for a few hours before the test, sorry I can't remember exactly how long, at least 2 I think. I would expect you to ve able to do the vaccines afterwards, if your horse isn't easily upset.
Ours had hay overnight, so she wasn't hungry and we removed the last bit, 2 or 3 hours (can't remember which) before the vet was due. Our horses are at home, so there was no coming and going of other horses to disturb her.