TORONTO - It might seem counterintuitive but it also appears to be true: Parents with more education were less likely to get their daughters vaccinated against HPV during the first year of British Columbia's free school-based program, a new study shows.

The finding of the study, published Tuesday in the journal PLoS Medicine, adds to a growing body of evidence that suggests vaccination efforts are being eroded not by people who are under-educated, but by upper-middle class folks with degrees.

"I think it's the combination of people who are used to making decisions, people who believe they can become experts by reading things on the Internet which would trump what public health officials or academics or doctors are saying," vaccine expert Dr. Paul Offit said when asked to comment on the study.

"They're used to making choices in their jobs and in their life, one. And two, they make those choices based on information. And the information that one gets here probably is primarily through places like the Internet, which is a source of both good and bad information about vaccines."

The study comes on the tail of another published Tuesday which showed that there has been a sharp increase in the percentage of U.S. parents who are refusing to vaccinate their children or delaying vaccination against the advice of the medical community.

That study, presented at an international conference in Vancouver, found 39 per cent of parents refused or delayed vaccinations for their children in 2008, up from 22 per cent in 2003.

Offit, who is chief of infectious diseases at the Children's Hospital of Philadelphia, was not involved in either study.

The HPV study was conducted primarily by researchers at the British Columbia Centre for Disease Control and the University of British Columbia.

The group surveyed parents of Grade 6 girls who had been eligible to get HPV or human papillomavirus vaccine through a free, school-based program in B.C. in the 2008-09 school year.

Lead author Dr. Gina Ogilvie said lots of studies had explored whether parents intended to let their daughters get vaccinated, but the group wanted to follow up to see what drove parents' decisions to grant or decline permission for their daughters to get the shot when it was available.

About half of the 4,000-plus randomly selected households agreed to take part. Just over 65 per cent of the daughters in those households had received the vaccine; 35 per cent of the parents had refused permission.

Parents were asked to describe the primary reason behind their decision and asked for secondary reasons as well.

Nearly half (47.9 per cent) of those who let their daughters get HPV shots said they did so because they had confidence in the effectiveness of the vaccine. Advice from a doctor and concern for the health of the daughter also played into yes decisions.

Among the parents who said no, concern about vaccine safety was listed as the major reason for the decision (29.2 per cent). A substantial portion - 15.6 per cent - felt their daughters were too young to get the vaccine and listed that as their major reason.

When the researchers compared the families that said yes and those that said no, interesting differences came to light.

Girls from two-parent households were less likely to have been given permission to get the shot. And parents with more education were more likely to have said no.

Ogilvie called it "the main surprise" of the study. "This is a flip from our traditional understanding," she said.

But Offit said this has also been spotted by researchers looking into trends in childhood vaccine rates.

A 2004 study by researchers from the U.S. Centers for Disease Control showed children of black, single mothers with no college degrees were more likely to be under-vaccinated - meaning they hadn't received all the recommended shots.

But children who hadn't received any shots at all "tended to be white, to have a mother who was married and had a college degree, to live in a household with an annual income exceeding $75,000 and to have parents who expressed concerns regarding the safety of vaccines and indicated that medical doctors have little influence over vaccination decisions for their children," said the study, published in the journal Pediatrics.

Offit said the trend is indeed a shift.

"The surprising part is that someone who would be better educated would be less likely to get the vaccine," he said. "That's exactly the opposite of what one saw say in the mid-1800s when smallpox vaccine was first required."

Ogilvie suggested a key lesson of her study for public health officials is that they have to do a better job getting accurate information about the safety and effectiveness of HPV vaccine to these types of parents.

"If this is where parents are getting information, we need to be there," Ogilvie said of the Internet.

"One of my big concerns is that in communities, very often ... educated parents can be opinion leaders for other parents. So we need to also make sure that those educated parents have at their disposal the balanced information and evidence-based information so they can make their decisions."