No vaccine is 100 percent effective in preventing disease. With the chickenpox vaccine, about 8 to 9 out of every 10 people who are vaccinated are completely protected from chickenpox. The vaccine almost always prevents against severe disease.
If a vaccinated person does get chickenpox, it is usually a very mild case with fewer skin lesions (usually less than 50) lasting only a few days, with no fever or a low fever, and few other symptoms.
Soreness, redness, or swelling where the injection was given are the most common side effects, occurring about 20 percent of the time.
A very mild rash or several small bumps can result in about 1 percent to 4 percent of people receiving the chickenpox vaccine.
As with any vaccine, there is a very small chance that serious problems could occur after getting the chickenpox vaccine. However, it is important to note that the risks from the chickenpox vaccine remain much lower than the risks from developing the disease itself.
(Click Chickenpox Vaccine Side Effects for more information on possible complications that can occur with the vaccine.)
Certain people should not receive the chickenpox vaccine or should wait. This includes people who:
- Have ever had a serious allergic reaction to chickenpox vaccine, neomycin, or gelatin (note: chickenpox vaccine does not contain egg).
- Currently have moderate or serious illness. People should wait until they recover from the illness. Chickenpox vaccine may be given to people with a mild fever, cold, or diarrhea.
- Are pregnant. Pregnant women should wait to get the chickenpox vaccine until after they have given birth. Women should not get pregnant for 1 month after getting the vaccine.
- Are unable to fight serious infections because of:
- Any kind of cancer or cancer treatment with x-rays or drugs (note: if your child has leukemia in remission, he/she may be eligible to receive the vaccine; ask your doctor)
- Treatment with drugs such as long-term steroids
- Receiving blood products (such as immune globulin or a transfusion) during the past five months.