The varicella vaccine immunizes the body against chickenpox, according to WebMD. The vaccine contains a weakened form of the varicella-zoster virus, making it less capable of triggering a harmful viral effect but active enough to prompt the desired immune system reaction.
Since the varicella vaccine provides immunity to chickenpox, it is recommended for any adults or children under 13 who have never contracted the illness, states WebMD. Chickenpox are easily spread through sneezing, coughing and skin contact, and children who frequently spend time in close quarters or high-traffic areas, such as schools and daycares, are highly vulnerable. In the United States, children typically receive the first varicella vaccine between the ages of 12 and 18 months and the second dose between ages 4 and 6. Individuals who receive the vaccine in late childhood or adulthood may have the second vaccine four to eight weeks after the first dose.
As of 2015, the varicella vaccine is approximately 85 percent effective at preventing chickenpox, according to KidsHealth. While vaccination is generally harmless, some individuals develop a short-term rash, tenderness or redness at the injection site, or experience mild fever and fatigue. The vaccine isn’t recommended for pregnant women, people with immune system deficiencies or people with allergies to gelatin or neomycin. Doctors also prefer not to vaccinate individuals taking steroid-based medications or undergoing conflicting treatments, such as chemotherapy or blood transfusions.