There are so many different types of Viruses that can cause Sickness, however the main ones are Rotavirus and Norovirus. Chances are that if the kids have Rotavirus you are already immune. However to be safe I would suggest, steam cleaning any carpets that have been contaminated with vomit. Then any hard surfaces clean with bleach based substance. Most stomach virus are not airbourne and can only be caught with direct contact, such as sharing kitchen utensils, or shaking hands with someone after they have vomited.
Also ensure that before you eat anything or put your fingers in your mouth, wash your hands thoroughly with Soap and Water, this will kill any virus that transmitted onto your hands.