Risk of chickenpox is on a rise after parents because of vaccine safety concerns have started rejecting immunization. Chickenpox cases dropped by about 80 per cent in the U. S. but after parents' refusal the matter is now concerning many.

Parents do not believe that chickenpox is a serious illness which is why they refuse the VZV vaccine. The vaccine is believed to be 10 per cent effective in preventing chickenpox.

Researchers from the Kaiser Permanente Institute for Health Research in Denver identified 133 children who got chickenpox from a group of close to 90,000 children enrolled in a Colorado health plan and compared them to 493 children who did not get the disease and matched for age, sex, age and length of enrollment in the health plan.

They found that children whose parents refused to get them vaccinated were nine times more likely to get chickenpox, also known as varicella.

"Many parents refuse the varicella vaccine because they think of chickenpox as a mild illness, but this is not necessarily true," study investigator Jason M. Glanz, PhD, of Kaiser Permanente tells WebMD.

The CDC recommends two doses of chickenpox vaccine to all healthy children who haven't had chickenpox. It is recommended for adults and older children too.