A young girl receives a vaccination at a clinic in...

A young girl receives a vaccination at a clinic in San Francisco. Credit: Getty Images, File 2009

Children whose parents staunchly oppose vaccination are nine times more likely to develop chickenpox than children who are fully immunized, researchers report in an analysis published Monday. Writing in the Archives of Pediatrics and Adolescent Medicine, researchers also report children whose parents refused vaccines were also more likely to develop complications requiring medical intervention.

"Historically, people have had a benign view of chickenpox but there can be serious costs in terms of absences from school and absences from work," said Dr. Andrew Adesman, chief of developmental and behavioral pediatrics at Schneider Children's Hospital in New Hyde Park.

"As a developmental pediatrician I often see families with concerns about autism and this is one of the primary reasons why families say they are reluctant to pursue vaccines," Adesman said.

He added that even though scientists have shown that the mercury preservative thimerosal once used in pediatric vaccines does not cause autism, many families continue to believe there is a link between vaccines and autism spectrum disorders.

Thimerosal was eliminated from pediatric vaccines nine years ago but the incidence of autism in children born after that time has continued to rise.

Adesman added if parents are refusing chickenpox vaccines, as the new research has found, it is also likely they are also refusing other inoculations. Measles and pertussis - whooping cough - have undergone a resurgence in recent years, and both can prove fatal. Studies have not yet demonstrated their uptick is related to vaccine-refusing parents.

Still, doctors say the majority of parents who are refusing vaccination came of age during a time when the range of childhood infections - chickenpox, measles, mumps, pertussis and diphtheria - no longer threatened children's lives. The infections, many parents say, are problems of a bygone era.

Indeed, in recent years it has become popular for some parents to take their children to chickenpox parties. The idea is expose children to an infected child and catch chickenpox, develop immunity and avoid vaccination.

"Vaccines are a victim of their own success," said Dr. Jason Glanz, the study's lead scientist and a medical investigator at the Kaiser Permanente Institute for Health Research in Denver.

"It's a paradox," Glanz added, noting that numerous myths and misunderstandings are flourishing about vaccines, despite scientific evidence that has dispelled them.

Known formally as varicella, Glanz said, chickenpox was a notable cause of serious complications such as encephalitis before the introduction of a vaccine in 1995. About 10,000 children were hospitalized annually and an estimated 100 died.Two doses of the varicella vaccine are recommended for school entry in New York, but only one dose is required.

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