Kids' Health: Chicken Pox Vaccine (Varivax)

Most toddlers in the United States are immunized against chicken pox (varicella), a typically mild disease. But in some cases, the disease can lead to several potentially serious—and life-threatening—complications such as pneumonia (an infection of the lungs) and encephalitis (an infection of the brain).

Once your child has turned 1, he can receive the chicken pox vaccine along with the MMR vaccine in separate injection sites. However, the vaccine is not recommended for children under 1 year of age. Additionally, it's not recommended for babies who are: allergic to any vaccine compounds (such as gelatin and neomycin), suffering from a blood disorder or cancer that impairs the immune system, receiving medications that suppress the immune system, suffering from active and untreated tuberculosis, or experiencing a fever. If your child does not receive the chicken pox vaccine simultaneously with the MMR vaccine, your doctor must wait four weeks before administering the chicken pox vaccine.

The chicken pox vaccine is approximately 98 percent effective in preventing severe forms of chicken pox, and it has minor side effects: redness, stiffness, soreness and/or swelling at the immunization site; fatigue; fussiness; fever; nausea; and, in 7 to 8 percent of cases, a temporary outbreak of bumps or pimples at the injection site about one month after the vaccine has been administered. Some children still develop a mild case of chicken pox after receiving the vaccine.