Chicken pox is a highly communicable disease. it may be transmitted by direct contact with a person infected with the varicella-zoster virus (vzv). the typical incubation time is between 10 to 20 days. a boy started school 2 weeks after showing symptoms of chicken pox including mild fever, skin rash, and fluid-filled blisters. one month after the boy returned to school, none of his classmates had been infected by vzv. what was the main reason?