Updated

More parents of teen girls not fully vaccinated against human papillomavirus (HPV) are intending to forgo the shots altogether - a trend driven by vaccine safety concerns, new research suggests.

That's despite multiple studies showing the vaccine isn't tied to any serious side effects but does protect against the virus that causes cervical cancer, researchers said.

"There were a lot of very sensationalized anecdotal reports of (girls) having bad reactions to the vaccine," said pediatrician and vaccine researcher Dr. Amanda Dempsey from the University of Colorado Denver.

"Safety concerns have always risen to the top of the pile, in terms of being one of the main reasons people don't get vaccinated, which is unfortunate because this is one of the most well-studied vaccines in terms of safety and is extremely safe," Dempsey, who wasn't involved in the new research, told Reuters Health.

The U.S. Centers for Disease Control and Prevention recommends that all kids - both boys and girls - receive three HPV shots as preteens.

Researchers led by Dr. Paul Darden from the University of Oklahoma Health Sciences Center in Oklahoma City got their data from a national immunization survey that involved phone calls to almost 100,000 parents.

They found that from 2008 to 2010, the percentage of teens who were up to date on their Tdap (tetanus, diphtheria and pertussis), MCV4 (meningococcal) and HPV vaccines all increased slightly.

Still, about three-quarters of girls ages 13 to 17 were not up to date on their HPV series in 2010. And the proportion of parents of those girls who said they didn't plan to get their daughters the rest - or any - of their HPV shots rose from 40 percent to 44 percent, the research team wrote Monday in Pediatrics.

At the same time, the proportion who cited safety concerns as their reason for abstaining from getting the HPV vaccine increased from less than five percent to 16 percent.

For all three vaccines asked about in the survey, other reasons parents gave for skipping their teenagers' shots included not thinking they were necessary, not having had a specific vaccine recommended by a doctor and, for the HPV vaccine, believing their child was not sexually active.

"These are wonderful vaccines preventing severe diseases," Darden told Reuters Health in an email. "HPV is the first vaccine that will prevent cancer which is a tremendous health benefit."

Dempsey said past research has suggested that although more girls are being vaccinated against HPV, vaccine rates haven't increased as quickly as for other shots, such as Tdap.

Darden reports having been a consultant for Pfizer, and one of his co-authors is on a safety monitoring board for vaccine studies funded by Merck, which makes Gardasil, one of the HPV vaccines.

Parents shouldn't rely on the media or Internet to learn about vaccines, according to Dempsey, since it's hard to tell what information is legitimate.

"If they have questions or concerns, they should trust their provider to give them accurate information about the vaccine," she said.