As your Dr should have told you, prednisone weakens your immune system and you need to take precautions around sick people and public areas, even more so now with the flu season. That is one of the main reasons my Dr refuses to use prednisone with me {or any of his patients} unless nothing else works. As for the IVIG, I don't know but Erin should know more about that.
I hope you get to being stronger soon