cathymcd I always lived in fear of vomiting bugs when my children were younger, I hate being sick and I hate having to look after others being sick.
As I understand it, and what I think mostly kept such things away, is endless hygiene. Be very careful about what you touch when out and about (wear gloves most of the time if you can, think of all those hands which touched the handrails etc before you!) and try not to touch your face with your fingers.
Then when you get home, wash your hands immediately and thoroughly with a bacteria-killing soap. If you're looking after children, get them into the habit of doing the same.
In the winter, I do more of cleaning kitchen counters with bleach spray or similar and I wipe door handles and make sure the toilet is kept extra clean. If someone in the family gets a vomiting bug, it's hard to stop it spreading, but I used to try to isolate that person, to get them to vomit into a basin that you can clean with bleach and to use a facecloth and towel for just that person while they were ill. I kept their clothes and the bedclothes, if changed, separate and washed them on a very hot wash.
My worst ever experience, just for the record, was one occasion being on my own for the weekend in the country with 10 month old twins and a 7 year old - as soon as I arrived at the house one of the twins began to vomit, later that day the other started. I got sick and I had to look after them whilst being sick and also the 7 year old who didn't succumb (wonderful immune system). When my husband appeared on the Monday, I had earned masses of Brownie points. I remember vividly sleeping on the floor on spread out sheets in front of the living room fire with both twins while we were all sick together!! I took home two black bags full of vomited-on clothes and cloths that had been used to mop up. What a weekend, one not to forget in a hurry! 