Unfortunately, this is a difficult question to answer. This is mainly due to the fact that some (up to 25%) people pick up the strep bacteria, and show no symptoms. These people become carriers of the bacteria and transmit it to others without actually becoming sick themselves. The majority of contacts, however, probably become symptomatic within the week.

Remember that those with strep throat are considered non-contagious after 24 hours of antibiotics. Therefore, if strep throat has not occurred in a contact within the week, the child probably won't catch it. But keep in mind, if a playmate gets strep throat and passes it along to other playmates in the group, the chain of infection may not break for several weeks.