Until the late 1990s, there were about 4 million cases of chickenpox a year in the U.S. Symptoms include fever, aches and itchy rash. Usually mild and uncomfortable, chickenpox is rarely dangerous. Rarely, a child with this disease develops encephalitis (brain inflammation) or dies. Once contracted, the virus stays in a person’s body and can reappear later in life as a very painful disease, called zoster or shingles.
This live viral vaccine has been used in the U.S. since the mid-1990s and is effective in preventing chickenpox in 70 to 90 percent of recipients and severe chickenpox in over 95 percent. The vaccine can cause mild soreness or a few chickenpox near the injection site.