Chickenpox Vaccine Slashes Virus by 90 Percent

Sept. 2, 2008— -- While researchers now say the chickenpox vaccine has slashed the occurrence of the disease in children by 90 percent, infectious disease experts remained concerned that too few parents take the disease seriously enough to get their kids vaccinated.

In a study released Tuesday in the journal Pediatrics, researchers from the U.S. Centers for Disease Control and Prevention report that the plummeting reports of chickenpox (also known as varicella) between 1995 and 2005 has dragged down chickenpox-related hospitalizations by 75 percent and reduced deaths by 74 percent -- with the greatest improvements in young children.

"The U.S. varicella vaccination program has dramatically reduced varicella incidence and related complications, hospitalizations and deaths," the authors conclude.

But they add that the effectiveness of a single dose of the vaccine -- about 85 percent -- is not sufficient to stop the spread of the virus in "high contact" settings, such as schools. They therefore recommend that a two-dose schedule be adopted for all children.

But infectious disease experts worry that too many parents may neglect to have their kids vaccinated for chickenpox -- in many cases because they believe the viral disease is not harmful.

"In my failing memory, chickenpox was responsible for 100-200 deaths per year in the U.S.," said Dr. James King, professor of pediatrics at the University of Maryland School of Medicine.

"It would be a virtual certainty that chickenpox would become widespread again if there were a reduction of the use of the varicella vaccine," he said. "It just amazes me that vaccines are not valued as they have been one of the most successful advances in medicine."

Dr. Gary Freed, director of the Division of General Pediatrics for the University of Michigan Health System, agrees.

"The public should [understand] how many hospitalizations and deaths were avoided by the use of the vaccine," he says.

Chickenpox Not Kid's Stuff

For anyone not born within the past couple of decades, however, chickenpox may seem less of a scourge and more of a rite of passage. Childhood memories of the scaly, red scabs, the itchy bumps and the smell of calamine lotion are common even among the 30-something set.

But Mark Slifka, associate scientist at the Vaccine and Gene Therapy Institute at the Oregon Health and Science University, says the very fact that most young Americans have been spared these unpleasant memories is a victory in and of itself.

"This is really quite an achievement," he says. "In just one generation, we have changed chickenpox from a virus that nearly every child had to suffer, to a virus that is causing only a handful of infections."

The benefits may not be just for the younger set. King says varicella infection is particularly hard on adolescents and adults. And even if parents don't catch the disease themselves, many may face an unenviable juggling act when it comes to balancing their work with caring for a child who will likely be sick for about seven days.

"I am ... amazed how economists do not place much of a financial value on a week's missed school, which is common," King says.

Parents, too, may lack concern over the potential health and financial implications of the illness. Some still adhere to the tradition of "chickenpox sleepovers," in which non-infected children are exposed to infected children in order to expose them to the illness, in essence allowing parents to plan for when their kids fall ill and subsequently develop chickenpox immunity.

"It is irresponsible for parents to purposefully expose their children to a wild-type virus when there is a vaccine available," Slifka says. "The vaccine is a vastly weaker strain of the same virus, and therefore much safer and with fewer side effects or disease complications."

"The chickenpox party is very 'old school,'" Freed says. "The key is having parents understand they can prevent disease.

"Even if the risk of hospitalization and death is relatively low, their children no longer need to experience the discomfort and suffering that is associated with chickenpox."

The End of Chickenpox?

But while a dose of the varicella vaccination may be effective -- and two doses even more so -- researchers say we are still a long way off from eradicating the illness.

"Unfortunately, it is unlikely that we will get rid of chickenpox in our lifetime," Slifka says, adding that the virus can "hide" in the body of seemingly healthy individuals, re-emerging years later in the form of shingles. "Since it can hide in otherwise healthy people for so long before 'jumping out' as infectious virus, it will be nearly impossible to completely eradicate it -- at least with the current vaccines that we have available at this time."

But the vaccine is a start. And Freed says that parents who downplay the importance of the vaccine or fear its use in their children must bear in mind the risks of the illness.

"The risk of the vaccine is far less than the risk of the disease," he says.