How do I avoid myself and my son getting sick? My two year old daughter is really sick her Dr…

How do I avoid myself and my son getting sick? My two year old daughter is really sick her Dr appointment is in the mornin. All she wants is to be held but I have a low immune system and have already went into preterm labor once and they gave me a shot. Should I worry? Is there anything I can take to prevent getting sick? Don't want to put stress on the baby but I have to baby my princess that is already here.