Can a vaccinated person who develops a mild case of chickenpox still spread the disease?

Yes. Vaccinated persons who get this milder form of chickenpox may still spread the disease to others who are not protected. Therefore, these individuals should stay at home until the blisters have formed scabs or if there are no blisters present, until no new spots or bumps are forming.

Chickenpox in children is usually not serious. Why not let children get the disease?

It is never possible to predict who will have a mild case of chickenpox and who will have a serious or even deadly case of disease. Now that there is a safe and effective vaccine available, it is not worth taking this chance. In addition, even mild cases of chickenpox can spread the disease, including to people at high risk of serious complications from chickenpox illness.

How do you get chickenpox?

Chickenpox is very infectious and spreads from person to person by direct contact with fluid from the rash or through the air from an infected person’s cough or sneeze. A person with chickenpox is contagious from 1-2 days before the rash appears until all blisters have formed scabs. It takes from 10-21 days after contact with an infected person for someone to develop chickenpox (this is the incubation period).

Is the vaccine effective in preventing chickenpox all the time?

No vaccine is 100% effective in preventing disease. For chickenpox vaccine, about 9 out of 10 people who are vaccinated with two doses are completely protected from chickenpox infection and almost 100% from 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, no fever or a low fever, and few other symptoms. This form of chickenpox is also called breakthrough disease, and is more common in those who only received one dose of vaccine.

What are the serious complications from chickenpox?

Serious complications from chickenpox include bacterial infections of the blisters, pneumonia, infection of the brain (encephalitis), and birth defects. Many people are not aware that, before a vaccine was available, there were approximately 11,000 hospitalizations and 100 deaths from chickenpox in the U.S. every year. About one child and one adult died each week; most of these persons were healthy or did not have a medical illness (such as cancer) that placed them at higher risk of getting severe chickenpox.

What is the chickenpox illness like?

The rash appears first on the trunk and face, but can spread over the entire body. In a person who has not received chickenpox vaccine, the infection can cause between 250 to 500 itchy blisters. Fever and headache may also be present. The illness usually lasts about 5-10 days. About one (1) unvaccinated child in 10 has a complication from chickenpox serious enough to visit a health care provider including infected skin lesions, other infections, dehydration from vomiting or diarrhea, flare-ups of asthma or more serious complications such as pneumonia or encephalitis (infection of the brain).

Certain groups of persons are more likely to have more serious illness with complications. These include adults, infants, adolescents and people with weak immune systems from either illnesses or from medications such long-term steroids. Chickenpox illness in a pregnant woman, especially during the first 20 weeks of pregnancy, can occasionally cause birth defects in the unborn baby.

People who have previously had chickenpox or been vaccinated occasionally still get chickenpox. They usually have a milder illness without fever and with fewer than 50 skin lesions, which may not form blisters and might not be itchy. The rash may look like bug bites and the illness usually does not last as long as in those who have never had chickenpox or the vaccine.

What is varicella (chickenpox)?

Chickenpox is an infectious disease caused by the varicella-zoster virus, which results in a blister-like rash, itching, tiredness and fever.

Who should be vaccinated?
  • Children aged 12 months, adolescents, and adults without evidence of immunity* should receive two doses of varicella (chickenpox) vaccine.
    • Children aged 12 months-12 years should receive their first dose of varicella-containing vaccine routinely at age 12-15 months. The second dose is recommended routinely at aged 4-6 years, but may be given earlier as long as it has been > 3 months since the first dose.
    • Children aged 13 years and adults should receive two doses of the varicella vaccine 4 to 8 weeks apart. If > 8 weeks have lapsed after the first dose, the second dose may be given without restarting the schedule.
  • Evidence of immunity to chickenpox includes any of the following:
    • Documentation of two doses of chickenpox vaccine;
    • Laboratory evidence of immunity or laboratory confirmation of disease;
    • Born in the US before 1980 (not considered evidence of immunity for health care providers, pregnant women or immunocompromised persons);
    • History of chickenpox based on healthcare provider diagnosis or verification;
    • History of herpes zoster based on healthcare provider diagnosis or verification.
  • A second dose catch-up chickenpox vaccination is recommended for children, adolescents, and adults, who previously received only one dose. The second dose can be given any time at least 3 months after the first dose for children <13 years of age and at least 4 weeks after the first dose for persons 13 years of age.
  • Persons who have serious allergic reactions to gelatin or other components of the chickenpox vaccine, who are pregnant, who have had a recent transfusion or other blood products, who are taking drugs such as steroids long-term that may affect the immune system, or who have a condition affecting the immune system such as HIV/AIDS or any cancer, should not receive chickenpox vaccine at this time and should consult their health care provider.
Why get vaccinated?

Chickenpox vaccine is the best way to prevent chickenpox, thereby protecting children and adults from the severe complications and death associated with the disease. Even with uncomplicated chickenpox cases, lost time from school and work and the cost of medications or treatment that may be needed can result in a significant cost for the family. At least one dose of chickenpox vaccine or evidence of immunity* is required for all children aged 18 months and older in licensed child care facilities and for all children entering a California school at kindergarten (K) level (or first grade if K was skipped) or transferring to a California school at any grade as of July 1, 2001.

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