Chickenpox Vaccine Reduces Illness, Costs

Widespread Vaccination Credited for Fewer Chickenpox-Related Hospitalizations

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Sept. 7, 2004 -- Less than 10 years since the chickenpox vaccine was recommended for widespread use in young children, a new study suggests it is already exceeding expectations in terms of reducing serious illness and hospital costs associated with chickenpox.

"The results show an annual savings of $100 million since the varicella, or chickenpox, vaccine was introduced, just in the cost of hospital care for people with severe cases. That's greater than the savings predicted in the vaccine's pre-approval analysis," says researcher Matthew M. Davis, MD, of the University of Michigan, in a news release.

The study compared hospitalization rates for chickenpox-related hospitalizations from 1993-2001. The American Academy of Pediatrics began recommending universal use of the vaccine in 1995 for children over 12 months of age.

The study showed hospitalizations declined by 74% during that time as use of the chickenpox vaccine increased. Researchers say it's the first study to show a drop in chickenpox-related hospitalizations in association with a rise in immunization rates.

Chickenpox is usually a mild infection, but it can have severe, even fatal complications. Before the vaccine, about one child in the U.S. would die every week from chickenpox. About one out of every 1,000 children with chickenpox will develop severe pneumonia or infection of the brain. In pregnant women, chickenpox infection can lead to birth defects such as mental retardation and shortened limbs.

Chickenpox Vaccine Successful

Before widespread vaccination, researchers found there was one chickenpox-related hospitalization each year for every 20,000 Americans, but by 2001, when about 76% of toddlers had been vaccinated, that number dropped to 0.26 hospitalizations per 20,000 people.

The biggest drop in hospitalization rates was among young children under 4 years who were the targets of the vaccination campaign. But hospitalization rates for chickenpox-related complications also decreased among youths aged 5 to 19 and adults.

The results appear in the September issue of Pediatrics.

Researchers say older children and adults may be reaping the benefits of the vaccination program among toddlers because they are being exposed to fewer infected children.


The study also showed that hospital charges for chickenpox-related illnesses have declined from $161.1 million in 1993 to $66.3 million in 2001, after adjusting for inflation. Hospital costs included charges for treating pneumonia or encephalitis in people with chickenpox; for hospital treatment during a chickenpox infection of people with AIDS, cancer, an organ transplant, or immune disorders; and for other known complications of severe chickenpox, such as skin infections.

Researchers say those savings do not include other health care costs related to chickenpox, such as doctor visits, prescription drugs, over-the-counter medications, and lost work time for parents or adult patients.

Based on the success of the child immunization program, researchers say older children and adults may be the next to be targeted for chickenpox vaccination in order to further reduce hospitalizations and complications.

For children 13 years and older and adults, the vaccination is given in two shots a month apart. Children aged 1 to 12 who have never had chickenpox need a single shot.

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SOURCES: Davis, M. Pediatrics, September 2004; vol 114: pp 786-792. News release, University of Michigan.
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