Everyone knows about this viral rash. Or they used to. A new vaccine means few kids get chickenpox anymore. You might have a fever or sore throat before the telltale itchy spots break out all over your body. It’s very contagious, so it’s best to stay home until all the sores crust over. Never give aspirin to a child with chickenpox. It can cause Reye’s syndrome, which is rare but serious.