U.S. parents still cold on HPV vaccine

The number of U.S. parents concerned about possible side effects from the human papillomavirus virus vaccine has grown despite the insistence from doctors that it is safe and efficacious against cervical cancer.

Over a three-year period beginning in 2007, those parents concerned about side effects from the vaccine rose by more than three times. The most common reason cited for parents refusing the vaccine in 2010 was that it was not necessary. The findings come from a recently released study published in the journal Pediatrics, according to NPR.

During the same period, the number of doctors recommending the vaccine to the parents of their patients rose from 47 percent to 52 percent.

"The large and increasing proportion of parents who do not intend to immunize their adolescent daughters with HPV is troubling," the study said, NPR reports.

The U.S. Centers for Disease Control and Prevention has recommended teenage girls receive the vaccine since 2007. CDC data shows that a little more than one third of those eligible have been administered the vaccine.

"We have not identified a significant likelihood of serious adverse events following vaccine," pediatrician and member of the CDC's Advisory Committee on Immunization Practices Joseph Bocchini said, according to NPR . "This is a very safe vaccine."