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Chickenpox (Varicella)

What is chickenpox?

Chickenpox (also called varicella) is a very contagious disease caused by the varicella zoster virus.

What are the symptoms of chickenpox?

Symptoms usually appear 10 to 21 days after exposure to the virus. Initial symptoms include sudden onset of a slight fever, feeling tired, and feeling weak. An itchy rash with tiny blisters soon appears first on the head, then on the stomach, chest or back, and eventually on the arms and legs. The blisters appear in small groups (referred to as crops) over several days. The blisters will dry, crust over and form scabs. There are usually more blisters on the chest and back than on the face, arms or legs.

How is chickenpox spread?

Chickenpox is spread from person-to-person by direct contact with the blisters or through the air when an infected person coughs or sneezes. People with chickenpox can spread the disease from 2 days before symptoms start until all the blisters crust over or form scabs (usually after about 5 days). However, people with weak immune systems are often contagious longer. Under Massachusetts regulations, people with chickenpox must stay out of school and work until all their blisters have dried and crusted over.

Is chickenpox dangerous?

Serious complications are rare, but chickenpox can lead to severe skin infection, scars, pneumonia, and brain damage. Serious complications are usually more common in newborns, pregnant women, people with weakened immune systems, and adults. In a person who has had chickenpox, the virus can become active years later causing a painful rash called shingles.

Who gets chickenpox?

  • Anyone who has not had chickenpox or has not been vaccinated against chickenpox can get the illness. It is most common among children younger than 15 years.
  • Babies younger than 12 months old are too young to be vaccinated and are at risk.

How can you prevent chickenpox?

  • The best protection against chickenpox is to be vaccinated.
    • Protect your children by having them vaccinated when they are 12-15 months old. A second dose of vaccine should be given at 4-6 years of age. If your child has missed a vaccine, ask your doctor about catching up.
    • Anyone 7 years or older who has not had chickenpox and was not vaccinated should also receive 2 doses; persons ages 7 years through 12 years should receive 2 doses, 3 months apart and persons ages 13 and older should receive 2 doses, 4 weeks apart.
    • Anyone who has not had chickenpox and received only 1 dose of vaccine should be given a second dose.
  • Vaccination is especially important for women who plan to have children (at least 1 month prior to becoming pregnant or postpartum), health care workers, and those who live with someone who has a weakened immune system.
  • Being vaccinated before any exposure to chickenpox offers the best protection; however, vaccination given within three to five days after an exposure may also provide some protection.
  • Some people who were not vaccinated and have not had chickenpox (such as newborns, pregnant women, and people with weakened immune systems) should see their health care provider immediately if they are exposed to someone with chickenpox because they can be given treatment (a pill or injection) that can provide some short-term protection if given soon after exposure. 

Massachusetts regulations require proof of immunity to varicella for school attendance, including college. Other groups, particularly healthcare workers, should also be immune to varicella.

Proof of immunity includes:

  • Written documentation of up-to-date varicella vaccination according Massachusetts school immunization requirements.
    • Massachusetts is currently phasing in requirements for varicella vaccination. Most students in kindergarten through college are required to have 2 doses of varicella vaccine or other proof of immunity. Some students, including child care and preschool students are only required 1 dose or other proof of immunity. For current Massachusetts school immunization requirements, click here.
  • Born in the United States before 1980 (this is not considered proof of immunity for healthcare providers or pregnant women)
  • Written documentation of a blood test confirming immunity
  • Written documentation of chickenpox diagnosed by a healthcare provider
  • Written documentation of history of shingles (Herpes zoster) by healthcare provider

Should pregnant women worry about chickenpox?

Pregnant women who have already had chickenpox disease or vaccination against chickenpox should be immune. Women who get chickenpox while they are pregnant are more likely than other adults to develop serious complications.  In some cases, chickenpox may be transmitted to the infant. Pregnant women who have not had chickenpox and are exposed to somebody with chickenpox should see their doctor immediately.

Can you get chickenpox more than once?

Yes, but it is very uncommon. Chickenpox disease generally results in lifelong immunity and most people will not get it again. However, the virus that causes chickenpox stays in your body for the rest of your life. Years later it can give you a painful rash called shingles.

Is the varicella vaccine safe?

Yes, it is safe for most people. However, a vaccine, like any medicine, is capable of causing problems like fever, mild rash, temporary pain at the injection site and allergic reactions. More severe problems are very rare. About 70–90% of people who get the vaccine are protected from chickenpox. If vaccinated people do get chickenpox, it is usually very mild.

Who should not get the varicella vaccine?

  • People who have serious allergies to gelatin or the drug neomycin should not receive the varicella vaccine.
  • People who have had a serious adverse reaction to a previous dose of varicella vaccine should not receive the varicella vaccine again.
  • Pregnant women should not get varicella vaccine until after delivery.
  • People with cancer, HIV, or other problems that weaken the immune system should check with their doctor or nurse before being vaccinated.
  • People who recently had a blood transfusion or were given other blood products should ask their doctor when they may get chickenpox vaccine since these products could temporarily reduce the effectiveness of the vaccine.
  • People with moderate or severe illnesses should not be vaccinated until after the fever and other symptoms are gone.

Click here to learn more about chickenpox from the Centers for Disease Control and Prevention.

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