How a Vaccine Slowed the Spread of Chicken Pox The highly contagious disease dates to ancient times and spread easily in households and classroomsâuntil the development of a vaccine. Author: blackjake/Getty Images The highly contagious disease dates to ancient times and spread easily in households and classroomsâuntil the development of a vaccine. Chickenpox is a highly contagious disease caused by the varicella-zoster virus that leads to itchy skin eruptions, which are sometimes compared to a “dew drop on a rose petal.” Until the development of a chickenpox vaccine in the late 20th century, the disease was a common childhood illness that could cause serious health problems in people who didn’t contract the disease until adulthood. More than four million people got chickenpox every year in the United States, resulting in more than 10,000 hospitalizations and 100 deaths. Since vaccinations began, those numbers dropped significantly.