Immunizations - Hepatitis A

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Side Effects of the Chickenpox Vaccine

Discomfort at the Injection Site. About 20% of vaccine recipients have pain, swelling, or redness at the injection site.

Mild Rash and Risk of Transmission. The vaccine may produce a mild rash within about a month of the vaccination, which has been known to transmit chickenpox to others. Individuals who have recently been vaccinated should avoid close contact with anyone who might be susceptible to severe complications from chickenpox, until the risk for a rash has passed.

Severe Side Effects. Between 1995 and 2001, 759 serious adverse effects were reported. Such events included seizures, pneumonia, anaphylactic reaction, encephalitis, Stevens-Johnson syndrome, neuropathy, herpes zoster, and blood abnormalities. Anecdotal reports have found a higher association of side effects when varicella vaccine is given at the same time as the measles, mumps, and rubella (MMR) vaccination. Because combined vaccinations are being developed, such effects should be closely studied.

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Long-Term Protection and Booster Shots

There is intense debate over the long-term protection of the vaccine. However, any negative studies to date on long-term effectiveness simply raise the question of the need for booster or higher doses -- not the elimination of the vaccine altogether.

Long-Term Protection in Vaccinated Children. Most studies suggest that the vaccine is not wholly effective in up to 30% of vaccinated children. However, they also report if chickenpox occurs, more than 95% of the cases are mild. It is also usually less contagious. In such people, the infection appears to be caused by a wild virus, not a reactivation of the vaccine. The longer the interval since vaccination occurs, the higher the risk for a breakthrough infection.

Long-Term Protection in Vaccinated Adults. The protective effects for adults are even less clear.

Vaccine's Effect on Shingles. A primary concern is whether the vaccine protects against shingles later on, particularly in people who have breakthrough infections -- however mild. As more and more children get vaccinated, the actual protection of the vaccine and the implication of the breakthrough infection will become clearer.

[For more information, see In-Depth Report #82: Shingles and chickenpox (Varicella-zoster virus).]

Review Date: 10/12/2010
Reviewed By: Harvey Simon, MD, Editor-in-Chief, Associate Professor of Medicine, Harvard Medical School; Physician, Massachusetts General Hospital. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.

A.D.A.M., Inc. is accredited by URAC, also known as the American Accreditation HealthCare Commission (www.urac.org).