I'm on Enbril and work in a school. I just take extra care to wipe surfaces and wash my hands A LOT! I get a flu shot. Like Susie, I have been sick less often, but when I do get sick, boy howdy, it's always a doozie! I only go off my Enbril when I have a viral or bacterial infection, or when I have surgery. I haven't had any problems staying on with minor infections, like ear infection or cut. In the ten years on biologics I have had only one bad bout with flu, shingles, pink eye, and bronchitis. I can name them because that's all I've had in ten years, but like I said...very sick with each.
My suggestion is to take precautions and if you do get sick, try to get on antibiotic or antiviral and go off biologic immediately. Otherwise, try not to worry about it too much.