Any tricks to prevent gastro/stomach bug?

My step daughter has a vomiting/pooping virus but is staying up at her Moms till shes better. My step son is with us, he isnt sick (yet) but im hoping he doesnt get it. Is there anything i can do to prevent him or the rest of us from getting it?? Ive got them all drinking grape juice. I am 36 weeks pregnant currently with a broken down washing machine. I will try ANYTHING if it means we can prevent the spread