Someone with chicken pox is usually contagious for the first 2 to 5 days of being sick BUT this includes the 1 to 2 days before you show symptoms with the rash. Which is a bummer. We are contagious before we know it. They normally say you should stay home 7 to 10 days if you have the chicken pox. The vaccine is very effective. Did someone you know get the pox?