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Disease information

Virus or bacteria

Chickenpox, or varicella, is caused by the varicella virus.

How it spreads

• Sneezing
• Coughing
• Physical contact with broken blisters
• Contact with virus particles that are sprayed in the air. The virus particles are spread in the air from broken blisters.

If 10 susceptible people are exposed to one infected person, 9 of 10 people will typically become infected with chickenpox.

Symptoms

• About 300-500 red bumps that turn to blisters
• Tiredness
• Fever
• Headache
• Vomiting
• Diarrhea

Typical disease timeline

Chickenpox typically lasts about 7 days.

Possible complications

• Severe pneumonia
• Encephalitis
• Blisters infected with bacteria, like Group A Streptococcus
• Birth defects (if a woman is infected during pregnancy)
• Guillain-Barré syndrome
• Thrombocytopenia
• Hemorrhage
• Arthritis
• Inflammation of the heart, kidneys, testes, liver or iris (colored part of the eye)
• Death (about 70 of every 10,000 children who are hospitalized)

Other things to know

• The varicella virus lives silently in the nerves after a chickenpox infection. It can reappear as shingles later in life.
• Chickenpox only occurs in people.

Vaccine information

The chickenpox vaccine is used to prevent chickenpox.

Before the chickenpox vaccine, one or two children in the U.S. died every week from chickenpox.

Vaccine type

• Live, “weakened” vaccines

Vaccine side effects

Common

• Pain, redness, swelling or soreness at the injection site (19 of 100 children; 24 of 100 adults)
• Low-grade fever (15 of 100 children; 10 of 100 adults)
• Rash with fewer than 10 blisters around the area of the shot or on other parts of the body (4 to 6 of 100 recipients)

Rare

• None

Very rare

• Serious allergic reaction (fewer than 1 of 1,000,000 recipients)
   

Other things to know

People who are allergic to gelatin should not get the chickenpox vaccine.

Reasons to get the vaccine

• Chickenpox still exists.
• Chickenpox can sometimes cause severe complications and even death.
• Some people can't get the chickenpox vaccine and require protection from others.
• Getting the chickenpox vaccine can offer protection from shingles as an adult.
• The chickenpox vaccine is safe.