I did go back on a biologic, Remicade, after having a serious bout of strep pneumonia & sepsis, due to the drug. I wound up in the ICU for a week, right after my loading doses. When I was finally home, I met with my GI & we had a long talk about
it- we both felt that I most likely had the pneumonia before I even got the initial Remi doses, & it just hadn't shown yet. I was so sick at the time anyway, & feeling so crappy, I wouldn't have thought much of it, feeling unwell was my daily norm! I believe I was also on pred at the time, which is no friend to infections. So, bottom line is I did go back on Remicade, but I had labs done before my next infusion, to see if everything was ok. I was also hyper-vigilant about
my health for awhile. I never have developed another infection, & have been on 1 biologic of another for years now. I always worry a little bit, though. And the Remicade never helped much after that experience- not sure if it was because the loading doses got screwed up, or what. I know exactly how you feel, it's very frightening.