U.S. health officials have noted a decline in chickenpox cases since the recommendation for a second vaccine was implemented in 2006. There has been an 85 percent decline in chickenpox cases since 2005. The largest decline was among five- to 14-year-olds, which is typical age group to receive the second vaccination.
Chickenpox was quite common prior to vaccination, with four million children contracting it annually back in the 1990s. The CDC suggests that vaccinations have prevented 3.5 million chickenpox cases, along with hospitalizations and deaths associated with chickenpox.
The chickenpox cannot be prevented 100 percent, but the disease is often milder and short-lived in those who have been vaccinated.
The single-dose vaccine was introduced in 1996, resulting in a 90 percent decline in cases. Ten years later, the second vaccine was recommended , further reducing the numbers of chickenpox cases.
In 2014, only 40 states reported cases of chickenpox.