Chicken pox

Chicken pox or varicella, infectious disease usually occurring in childhood. It is believed to be caused by the same herpesvirus that produces shingles. Chicken pox is highly communicable and is characterized by an easily recognizable rash consisting of blisterlike lesions that appear two to three weeks after infection. Usually there are also low fever and headache. When the lesions have crusted over, the disease is believed to be no longer communicable; however, most patients simultaneously exhibit lesions at different stages of eruption. Chicken pox is usually a mild disease requiring little treatment other than medication to relieve the troublesome itching, but care must be taken that the rash does not become secondarily infected by bacteria. Pneumonia and encephalitis are rare complications. A vaccine for chicken pox was approved for use in the United States in 1995. The drug acyclovir may be used to treat the disease, particularly in older patients.

In 1995, the American Academy of Pediatrics began recommending that the varicella, or chicken pox, vaccine be given to all children between 12 and 18 months of age. Prior to the vaccine's availability, an average of 50 otherwise healthy children died each year from chicken pox and related complications.

Today, 20 states require children to get the vaccine before they can enter childcare or preschool. The Centers for Disease Control is particularly active in promoting the benefits: The vaccine has prevented childhood deaths, lessened the risk of complications, reduced the number of missed school days, and decreased the danger for people who can't be vaccinated (pregnant women, infants under 1 year of age, and children with compromised immune systems).

Although research shows that the vaccine's effectiveness is about 85 percent — and can decrease overtime — and that a small percentage of immunized kids can still get a milder case of the chicken pox, Yale University researchers found that the shot offered excellent protection against the disease eight years after it was given.

Putting a stop to chicken pox

Help prevent chicken pox (varicella) by encouraging susceptible patients to be vaccinated with Varivax, as recommended by the Centers for Disease Control and Prevention (CDC). Below is some information about the vaccine.

Why recommend vaccination?

Many children and adults are hospitalized each year with chicken pox. In the United States, about 100 people die each year from chicken pox.

Who should be vaccinated?

Vaccination is recommended for adults and children age 1 year or older who don't have a history of chicken pox, health care professionals, those who live or work in any crowded setting, and anyone in contact with immunosuppressed people.

Who should avoid vaccination?

Because the vaccine contains live virus, it's contraindicated for pregnant women, immunocompromised people, people with untreated active tuberculosis, children on steroids or immunosuppressive therapy, and those with a generalized malignancy. It's not known if the virus is excreted in breast milk. Don't give the vaccine within 5 months of administration of varicella-zoster immunoglobulin or a blood transfusion. Varivax isn't recommended for people who have a history of anaphylactic reaction to any vaccine components.

How effective is the chicken pox vaccine?

It provides 70% to 90% protection against infection and 95% protection against severe infection for an estimated 7 to 10 years.

How do I administer Varivax for chicken pox?

Reconstitute it according to the package insert and use it within 30 minutes or discard it. Give a 0.5-ml dose S.C. in the upper arm or the anterolateral thigh. Give a single dose to children 1 to 12 years old. Anyone older than 12 requires a second dose 4 to 8 weeks after the first dose. You may give Varivax at the same time as other vaccines but at a separate site.

How common are adverse reactions to the chicken pox vaccine?

About 20% of vaccine recipients experience soreness, redness, swelling, or rash at the injection site after vaccination. A few recipients have experienced high fever, contagious breakthrough varicella infection, or upper respiratory infection.

What about long-term risks of chicken pox?

The vaccine hasn't been evaluated for its carcinogenic or mutagenic potential or its effect on fertility; women should avoid pregnancy for 1 month after vaccination to avoid harming an unborn child. The vaccine's live virus could emerge later in life as shingles.

After vaccination, he should avoid contact with newborns, pregnant women who haven't had chicken pox or been vaccinated, and immunocompromised people for 1 month. Advise him to call his health care provider if he experiences severe adverse effects. Tell him that he may need a booster in the future.

Last updated Jan 4/07