Ant-vaxxers risk to vaxxers children?

Say a child who has been vaccinated has a seriously compromised immune system due to disease or medical conditions. A child who, when coming down with a flu or cold that is mild to others, usually becomes so ill that hospitalization is required. How big is the risk to their health if exposed to a non-vaccinated child who becomes ill?

Sorry if the question isn't clear. I'm just trying to determine the risk that non-vaxxer's present to vaccinated, but unhealthy children.

via International Skeptics Forum http://ift.tt/1nxDv58