When a person has the flu they are contagious with the flu for one day before developing symptoms and up to five to seven days after becoming ill with the flu.
So if you do have the flu avoid contact with people if possible for at least 5 to 7 days after you get the flu to avoid infecting other people.
Keep your kids home from school and stay home from work if possible until the flu is over with.
You won't be feeling very good anyway to work and you can die from the flu so always stay home until you or your kids are no longer contagious with the flu.
I've stayed home from work for a week to make sure I was no longer contagious and then I returned to work.