Varicella (chickenpox) is a very common childhood disease. It's usually mild, but can be serious, especially in young infants and adults. Varicella is caused by the varicella-zoster virus (VZV), a form of the herpes virus. Varicella is a highly contagious virus that is spread from person-to-person through the air or by contacting the fluid from the blisters caused by the virus. Chickenpox causes a blistering itching rash (pox), fever, and fatigue. It can lead to more serious illness including severe skin infection, scars, pneumonia, brain damage, and death.
Immunization with the chickenpox vaccine can prevent chickenpox in most people. If a person contracts chickenpox after getting the vaccine, he or she will usually have a very mild case and be less contagious to others.
In the past, more than 90% of adult Americans had been infected with chickenpox. Since 1995, a chickenpox vaccine has been available for children 12 months of age and older. Adolescents and adults who have never had chickenpox can also get the vaccine. The vaccine has proven very effective in preventing severe chickenpox. Experts recommend that all healthy children be vaccinated with the chickenpox vaccine between 12 and 15 months of age. A second dose is recommended at age 4 to 6 years, generally given at the same time as other required preschool vaccinations.
Many schools now require vaccination prior to entry into preschool or public schools. Catch-up immunization may be given as needed between the ages of 7 to 18 years, and to adults.
Children who are sick with another illness or have a fever should wait until they are well to receive the chickenpox vaccine. Some children should not receive the chickenpox vaccine. These include children who have ever had an allergic reaction to gelatin, the antibiotic neomycin, and children who have had a previous reaction to chickenpox vaccine. Your child's health care provider will advise you on the vaccine in these and other situations.
A vaccine, like any medication, can cause serious problems, such as severe allergic reactions. The risk of chickenpox vaccine causing serious harm or death is very small. Most people who get the chickenpox vaccine do not have any problems with it. Problems may include:
Soreness or swelling in the location where the shot was given
Mild rash, up to one month after vaccination
Other problems such as low blood count, pneumonia, seizures, and severe brain reactions are very rare. Experts are not sure whether these are caused by the chickenpox vaccine or not.
You may want to treat fever or pain at the injection site with an over-the-counter medication such as acetaminophen or ibuprofen. There is no evidence that giving medication before the injection will prevent fever or pain although there is some evidence that it may actually reduce the effectiveness of the vaccine.
An allergic reaction would most likely occur within a few minutes to a few hours of the shot. Signs of an allergic reaction may include difficulty breathing, wheezing (squeaking sounds while breathing due to tight airways), weakness, fast heartbeat, hives, and paleness. Report these or any other unusual signs immediately to your child's health care provider right away.