New research has found that 44% of US parents will not allow their children to be vaccinated with GlaxoSmithKline’s Cervarix or Sanofi Pasteur/Merck & Co’s Gardasil.

This is according to new research in the US journal Pediatrics, which analysed data from an American national survey from 2008 to 2010 on immunizations for teenagers.

The proportion of parents saying they wouldn’t vaccinate their teens against the human papilloma virus rose to 44% in 2010 from 40% two years earlier, according to the report.

“That’s the opposite direction that rate should be going,” said Robert Jacobson, a paediatrician at the Mayo Clinic Children’s Center in Rochester, Minnesota, and a senior researcher of the paper, said in a statement.

“HPV causes essentially 100% of cervical cancer and 50% of all Americans get infected at least once.”

HPV is the most common sexually transmitted infection with around 20 million Americans having the disease, according to the US Centers for Disease Control and Prevention.

GSK’s Cervarix and Sanofi Pasteur/Merck & Co’s Gardasil and the two main vaccines against the disease, which work by immunising young girls against the sexually transmitted HPV virus, which is estimated to cause 70% of all of cervical cancers.

But HPV vaccination has been a contentious area, as the immunisation process can begin in girls as young as nine years old, and some parents are concerned about the side effects of the drugs on their children.

There have been no serious safety concerns from any drug regulators over the two vaccines, but this report shows that parents are still wary of the treatments.