Varicella (chickenpox), according to the CDC, is "a very contagious disease caused by the varicella-zoster virus (VZV). It causes a blister-like rash, itching, tiredness, and fever."

Varicella History
In 1767, English doctor William Heberden first distinguished chickenpox (varicella) from smallpox (variola major and variola minor). In 1892, Hungarian pediatrics professor James Bokay wrote of the connection between chickenpox and later contraction of shingles; his theory was be proven correct in 1925 by K. Kundratitz, MD. Thomas Weller, MD, first isolated the varicella virus in 1953. In 1974, Michiaki Takahashi, MD, attenutated (keeping the virus live but weakening it so that it is essentially harmless) the varicella virus, creating a vaccination. A version of that vaccine, Varivax, was licensed and used in the United States in 1995 and, as of June 25, 2014, remains the only varicella vaccination used in the United States.

Below are three graphs. The first shows the number of varicella (chickenpox) cases in the United States, adults and children, from 1972 to 2011. The second graph shows the number of deaths caused by the varicella virus in adults and children from 1972 to 2011. And the third graph shows the varicella vaccination rates among children aged 19 to 36 months in the United States since Varivax was licensed for use.

As of Aug. 18, 2014, the CDC recommends that children receive the first dose of the varicella vaccination between 12 and 18 months of age.
varicella zozter virus
Microscopic view of the varicella virus
Source: Jon Lieff, "The Remarkable Intelligent Varicella Virus," www.jonlieffmd.com
, Feb. 23, 2014
Varicella Cases
Varicella Deaths
Varicella Vaccination Rates
Related Links: 1. MMR vaccine
2. DTap vaccine
3. Polio vaccine
4. Hep B vaccine
5. Hib vaccine
Sources:

CDC, "Chickenpox (Varicella): Overview," www.cdc.gov, Nov. 16, 2011

CDC, "Reported Cases and Deaths from Vaccine Preventable Diseases, United States, 1950-2011,"  www.cdc.gov, Jan 20, 2012

CDC, "U.S. Vaccination Coverage Reported via NIS," www.cdc.gov, Mar. 11, 2014

College of Physicians of Philadelphia, "The History of Vaccines: Timelines, Diseases and Vaccines," www.historyofvaccines.org (accessed June 25, 2014)