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Most U.S. Kids Now Vaccinated Against Chickenpox

Ten years after inoculation's launch, 85 percent are immunized

TUESDAY, April 19, 2005 (HealthDay News) -- Ten years after a vaccination was developed to prevent chickenpox, approximately 85 percent of American children have been inoculated against the disease, closing in on the 90 percent rate set by health officials.

"We've made very rapid progress in the last 10 years, although we still have some distance to go," said David Neumann, executive director of the National Partnership for Immunization (NPI), a non-profit organization that works with public and private organizations to promote immunizations.

Neumann spoke Tuesday at an NPI-sponsored teleconference to release its findings from its Chickenpox Report Card.

Among the good news: Neumann reported that all but six states have now mandated that children entering day care or elementary school must have proof of vaccination against chickenpox, known in medical parlance as varicella.

This requirement, he said, has been the key to dramatically increasing the numbers of children aged 19 months to 35 months who have been inoculated -- up from 12.2 percent in 1996 to 88 percent in the first quarter of 2004.

The result, Neumann said, "is that incidence of the disease has declined more than might have been predicted. Further, as more children are vaccinated against the disease, the incidence has declined among other groups as well."

Chickenpox is a highly contagious disease that can cause serious health problems, including severe skin disorders, pneumonia and, rarely, brain swelling, called encephalitis. Before the vaccine was introduced, health officials estimate that as many as four million people had been infected with chickenpox, with approximately 11,000 of those patients requiring hospitalization.

The drop in incidence in the last decade has caused a 75 percent decline in hospitalizations for chickenpox since 1995 along with a drop in chickenpox-related deaths during the same time period, from 100 deaths annually, to just nine by 2004.

Neumann said, however, that these high compliance numbers, while encouraging, mean that there are still 600,000 American children a year who are not being vaccinated.

Also, rates of immunization vary significantly from state to state, with Connecticut reporting a 93.2 vaccination rate among young children, compared to a 68.4 rate in South Dakota. Only 16 of the 44 states that require immunizations reported a vaccination rate of 87.4 or higher among children aged 19 to 35 months.

The vaccine was approved for use in March 1995, and the U.S. government's Healthy People 2010 goal is to vaccinate 90 percent of children ages 19 months to 35 months and adolescents ages 12 to 15 years to lower the rates of infectious diseases like chickenpox.

Another concern among health professionals who spoke at the conference is the number of older children who entered school before the vaccine was developed -- children who never caught the disease because its incidence had declined, and who are now at risk for it in their teenage years. When chickenpox strikes this age group, the risks for serious side effects are up to 20 times higher than if it strikes during early childhood, Neumann said.

"There are a lot of un-inoculated children approaching adolescence, and we need to require proof of immunity or proof of the disease from a doctor," said Dr. Richard Jacobs, chief of pediatric infectious diseases at Arkansas Children's Hospital, who also participated in the teleconference.

Only 22 states require vaccines for children entering middle school, Neumann said.

However, all the experts agreed the chickenpox vaccination campaign is on the right track.

"We are happy to see that incidence has dropped in all age groups, and are very pleased to see the success of the vaccine," said Dr. John Modlin, chairman of the department of pediatrics at the Dartmouth Medical School in Hanover, N.H.

More information

For more on chickenpox and the vaccine, visit the U.S. Centers for Disease Control and Prevention.

SOURCES:David Neumann, Ph.D., executive director, National Partnership for Immunization, Alexandria, Va.; Richard Jacobs, M.D., chief of pediatric infectious diseases, Arkansas Children's Hospital, president, Arkansas Children's Hospital Research Institute, Little Rock; John Modlin, M.D. chairman of the Department of Pediatrics, Dartmouth Medical School, Hanover, N.H.; April 19, 2005, press teleconference, Chickenpox Report Card
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