I'm on Remicade infusions and I was told that I was not supposed to use biologics when sick. You might want to talk to your gasto.
I was on Imuran as well as Humira and I never got sick, even after being around people who were. Maybe I was just lucky.
Keep hand sanitizer with you at all times. Remember not to touch your face as well, and get lots of rest!
Viruses are no different from bacterial infections as far as immunity.