Chickenpox (Varicella)

Chickenpox (varicella) is a common, very infectious childhood disease caused by the varicella virus. It appears as an itchy rash that looks like water blisters.

What are the risks of getting chickenpox disease?

  • Most children recover from chickenpox. However, some will become very sick. Chickenpox can lead to pneumonia or problems with body organs, such as the brain, liver or heart.
  • The blisters can become infected and cause scarring, or you can end up with a serious infection that can lead to flesh-eating disease.
  • Chickenpox can be very severe or even life-threatening for newborns, adults or those with a weak immune system. Unborn babies who get chickenpox from their moms may have birth defects.
  • A person who has had chickenpox can get ‑shingles years later.

Getting the chickenpox vaccine is much safer than getting the disease.

How well does the vaccine work?

  • About 97% of people given 2 doses of vaccine are protected against chickenpox. The other 3% usually have a milder case of chickenpox because of the vaccine.

What is in the vaccine?

  • It has a tiny amount of the chickenpox virus that has been weakened so the vaccine doesn’t give you the disease.
  • It has a very small amount of an antibiotic in it to prevent the cell culture from being contaminated with bacteria.

When is the vaccine given?

  • The first dose is given at 12 months old and the second dose between 4-6 years old.
  • 2 doses, 6 weeks apart are needed for anyone 13 years old or older who hasn’t already had chickenpox or the vaccine.

What are the risks with immunization?

  • Some people will have a red, swollen and sore arm where the needle was given for 1-2 days after the immunization.
  • Some will develop a mild fever and a few chickenpox-like spots 7-14 days after the vaccine.
  • As with any vaccine, unexpected or unusual reactions can happen. Severe allergic reactions are very rare.

The following people should not be immunized with the chickenpox vaccine:

  • children with severe allergies to components in the vaccine
  • children with a weakened immune system (caused by illness or by taking certain types of medicine, like steroids)
  • pregnant people