Chickenpox vaccine should help adults

By KAREN UHLENHUTH
Associaed Press

Chickenpox in adults is rare -- and often severe.

Patsy Mink, a 74-year-old congresswoman from Hawaii, died last month of viral pneumonia brought on by chickenpox. This unusual turn of events is likely to become even more unusual in the future, thanks to the chickenpox vaccine.

It was introduced in 1995, and by 2000, 68 percent of 19- to 35-month-olds had been vaccinated. Most health care providers aim to keep nudging that number higher.

"If we can get all kids vaccinated, and if the vaccine's effectiveness lasts, this type of thing should become very rare," said Paul Jost, an infectious disease specialist in Kansas City. "We're talking a few decades before it will have a full impact."

Although they were born long before the vaccine came along, adults almost never get chickenpox because the virus was ubiquitous when they were children. Getting the disease effectively inoculated them.

Perhaps as few as 1 in 1,000 adults lack antibodies to chickenpox, estimated Daniel Hinthorn, a professor of medicine and the chief of infectious disease at the University of Kansas Medical Center. Exposure to the virus stimulates the production of antibodies that tend to prevent a recurrence, he said.

Adults who've never been exposed to chickenpox nor had the vaccine generally experience much more severe symptoms than children do if they develop the illness.

"Chickenpox in adults we always take very seriously," Jost said. "You can get pneumonia and encephalitis -- even someone in their 30s or 40s."

According to the Centers for Disease Control and Prevention, people 20 years and older account for fewer than 5 percent of chickenpox cases and about 55 percent of deaths from the virus.

For that reason, a vaccine generally is recommended for adults who've never been exposed to the chickenpox virus. It's important to verify that an adult doesn't already have antibodies, Hinthorn said. Many people who say they never were exposed to the virus in fact have been and have the antibodies to prove it.

"Every vaccine has potential for problems," he said. "You wouldn't want to have a vaccine-related event when you didn't need it."

Although routine immunization for children is supported by many health care providers, some say that it is not necessary and that children build stronger immune systems if they get chickenpox.

While the antibodies the body manufactures in response to the illness tend to be effective for life, the antibodies stimulated by a vaccine are less understood. Some studies indicate they are effective for at least 25 years. Whether they last a lifetime without a booster shot, Jost said, is a still unanswered question.