Varicella zoster virus vaccine

Alternative names
Chickenpox - vaccine; Varivax; Vaccine - chickenpox

This vaccine protects against chickenpox, a disease caused by the varicella-zoster virus. Chickenpox is characterized by a rash that forms blisters and is generally mild. However, some children can develop serious, even life-threatening, complications from chickenpox.


The American Academy of Pediatrics (AAP) and the Centers for Disease Control and Prevention (CDC) recommend the chickenpox vaccine for children over 12 months.

People 13 and older who have not received the vaccine and have not had chickenpox should get 2 doses 4 to 8 weeks apart. Children who receive the vaccine before age 13 only need to receive 1 dose.

Chickenpox is a caused by the varicella-zoster virus (VZV). It is very common and highly contagious, occurring more often in the winter and spring. Generally, the infection is mild and not life-threatening, but there are thousands of cases each year in which people become seriously ill, requiring hospitalization, and some people do die from it.

Chickenpox vaccine is required for school entry in a growing number of states.

The following are generally considered acceptable proof of immunity:

  • A history of having chickenpox  
  • Showing that you have had the vaccine  
  • Showing a blood test result that indicates immunity to chickenpox

The vaccine is highly effective for the prevention of chickenpox. However, a small number of people will still get chickenpox, despite having received the vaccine. Such cases are generally milder than those seen in unvaccinated people.

The chickenpox vaccine provides long-term immunity to the disease, and booster immunizations do not appear to be necessary, though this is still under study.

Chickenpox vaccine is also effective for the prevention of chickenpox in unimmunized children recently exposed to chickenpox (post-exposure immunization). Consult your doctor if you believe that your child has been exposed.

The side effects from the chickenpox vaccine are generally minor.

Some of the mild possible side effects include:

  • Fever  
  • Pain and swelling in the shot location  
  • A mild rash

Only in very rare instances have more moderate or severe reactions been reported, including:

  • Seizures (less than 1 out of 1,000 children).  
  • Pneumonia (very rare).  
  • A true allergic reaction (anaphylaxis), which could cause difficulty breathing, hives, wheezing, fast heart rate, dizziness, and changes in behavior. These can occur anywhere from a few minutes to a few hours after the injection. This is extremely rare.  
  • Other reactions, such as low blood counts and brain involvement, are so rare that their association with the vaccine is questionable.


  • Pregnant women should not be given the vaccine, and women who have received the vaccine should wait at least 1 month before getting pregnant.  
  • Children or adults who have a weakened immune system as a result of HIV/AIDS, cancer, organ transplants, or other factors should not be vaccinated for chickenpox.  
  • Children or adults who are allergic to the antibiotic neomycin or gelatin should not receive this vaccine.  
  • Children or adults taking steroids for any condition should consult with their doctor about the proper timing of chickenpox vaccine.  
  • Anyone who has recently received a blood transfusion or other blood product (including gamma globulin) should consult with their doctor about the proper timing of the chickenpox vaccine.  
  • Children receiving aspirin or other salicylates should not receive this vaccine because of the theoretical risk of Reye’s syndrome.


  • You are uncertain as to whether the chickenpox immunization should be given.  
  • Any moderate to severe side effects appear after the injection.  
  • Any symptoms occur after the vaccine that alarm you.  
  • You have any other questions before or after receiving the vaccine.


Johns Hopkins patient information

Last revised: December 3, 2012
by Levon Ter-Markosyan, D.M.D.

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