Unless vaccinated, nearly everyone will become infected by chickenpox, most often in early childhood or later on when complications are more likely. In the United States before a vaccine was available, chickenpox infected 3.7 million people a year, hospitalized more than 10,000, and killed 100, about 40 of whom were children.

Controversies surround the current recommendation to give chickenpox vaccine to all U.S. infants. A great concern is that the immunity from the vaccine may wear off years later, when the individual is much older and so has a far greater risk for complications from the disease. Also, because chickenpox is considered a relatively mild childhood disease, some parents believe that vaccination is unnecessary. Complaints have been raised that this is a "designer vaccine," meaning it was developed for parents' convenience, so they wouldn't have to miss work. Use of the vaccine is increasing, though: in 1997, 26 percent of 2 year olds were vaccinated against chickenpox, whereas just a year later, 43 percent were vaccinated. As of this writing, chickenpox vaccine requirements have been enacted in 14 states, with more on the way