Chickenpox is a very contagious disease caused by the varicella zoster virus. Chickenpox causes an itchy rash that scabs over and usually lasts about a week. Scratching the scabs can cause permanent scarring. Chickenpox can also cause fever, tiredness, loss of appetite, and headache.
Even in healthy children, chickenpox can be severe. Chickenpox is often more severe in infants, older children, and adults. Rare but serious complications include skin infections, pneumonia, inflammation of the blood vessels, swelling of the brain and/or spinal cord covering, and infections of the bloodstream, bone, or joints. Some people who had chickenpox as a child can get a painful rash called shingles (also known as herpes zoster) decades later. If a person gets chickenpox during the first half of pregnancy, the varicella virus can cause severe birth defects.
The chickenpox vaccine needs 2 doses for the best protection. When children get both doses, the vaccine is more than 90% effective at preventing chickenpox and close to 100% effective at preventing severe chickenpox. No vaccine is a 100% guarantee that a person will not get the disease, but it is unlikely a fully vaccinated person will get chickenpox. Even if they do get chickenpox, it will likely be mild with few or no blisters and low or no fever.
Also, if a child is vaccinated for chickenpox they are less likely to get shingles in later childhood and adolescence, and possibly adulthood.
The chickenpox vaccine is very safe. Like any vaccine or medication, there can be side effects, but they are usually mild, including:
- Soreness in the arm where the vaccination is given (in about 1 out of 5 children)
- Mild rash that can occur up to one month after vaccination (in about 1 out of 25 people)
- High temperature that goes away in about a day
Mild vaccine reactions are normal and signs the body and vaccines are working together to create an immune response to protect against chickenpox. Very rare side effects can include pneumonia or fever-related seizures. The fever, not the vaccination, causes the seizure. While we understand that seizures can be scary for parents, it’s important to understand that these types of seizures are almost always harmless.
A child should receive the 1st dose of the chickenpox vaccine between 12 and 15 months old and should get a booster at 4 to 6 years of age. A child who was not vaccinated on time, and is between 6 – 13 years old, can get the 2 doses 3 months apart. If you or your child are over 13 years old, talk to your doctor.
There may be other vaccines that your child should get at the same time as the chickenpox vaccine, and there may be some children who shouldn’t get this vaccine. Talk to your healthcare provider about what vaccines your family needs. Use our Vaccines Booklet to prepare for your child’s vaccine appointments.
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