Anaphylaxis is a severe allergic reaction, with symptoms including nausea, rashes and difficulty in breathing, which can be treated easily if identified at an early stage. Side effects also included high rates of fainting among adolescents which could lead to serious head injuries, according to the report.

But Halsley added that these adverse reactions are rare and that the cause of anaphylaxis among Australian children remains unclear.

From the HPV vaccine doses administered in schools, seven cases of anaphylaxis were identified, which represents an incidence rate of 2.6 per 100,000 doses.

Yet Halsley said while these rare but serious adverse effects highlight the importance of vaccine safety studies and “careful management in immunization clinics,” they shouldn’t discourage the administration of the vaccines in school clinics.

Jacinthe Perras, spokesperson for the Public Health Agency of Canada, said Gardasil underwent extensive testing and clinical trials before it was approved for use in Canada two years ago. The risk of anaphylaxis or any adverse reaction is very low, she said in an e-mail to The Catholic Register.

No confirmed cases of anaphylaxis after HPV immunization were reported in Canada. And from July 2006 to August 2008, only 220 cases of adverse effects have been reported to the agency, Perras said.

There have been an estimated half-million doses of Gardasil distributed across Canada since it was licensed.

Meanwhile, in an Aug. 21 editorial in the New England Journal of Medicine, Dr. Charlotte J. Haug said serious questions are still left unanswered. For instance, researchers still have not proven whether the vaccine will prevent cervical cancer and death.

“Despite great expectations and promising results of clinical trials, we still lack sufficient evidence of an effective vaccine against cervical cancer,” Haug wrote.

The HPV vaccine’s effects “will not be observable for decades,” she continued.

“With so many essential questions still unanswered, there is good reason to be cautious about introducing large-scale vaccination programs,” Haug wrote. “Instead, we should concentrate on finding more solid answers through research rather than base consequential and costly decisions on yet unproven assumptions.”

Haug also noted the pressure on policy makers worldwide to introduce the vaccine in national or state-wide vaccination programs.

Canada’s Conservative government set aside $300 million for a national Gardasil vaccination program last year. Catholic groups raised objections, arguing that the vaccine could encourage sexual activity in young girls. The vaccine is said to be most effective for 11- or 12-year-old girls.

The Calgary and Edmonton Catholic school boards will be launching new HPV vaccination programs this year. Alberta’s bishops sent a letter of caution to parents on June 24.

“At best, a vaccine can only be potentially effective against one of these risks, that to physical health, and may have other unintended and unwanted consequences,” they wrote.

“Catholic teaching is that sexuality is a God-given gift that should be reserved for marriage.”

The Edmonton and Calgary boards’ programs will form part of the Alberta government’s three-year, $20-million-per-year Gardasil vaccination program for more than 40,000 girls in Grades 5 and 9 beginning in September.

Lori Nagy, spokesperson for the Edmonton Catholic School District, said the board is supporting the Edmonton archdiocese’s document which says that parents are the primary decision-makers in the health care matters of their children. Nagy said the Edmonton Catholic School District is keeping parents updated about the vaccine.

“I do know that some parents are concerned about the vaccine. That is why we will send a lot of information home for them,” she said during a telephone interview from Edmonton.

This year, the Edmonton Catholic board will offer the vaccine to Grade 5 girls in 63 schools with 14,000 students. In 2009, Grade 9 girls in 25 schools with 7,500 students will have access to the vaccine. Free vaccinations began last year in Nova Scotia, Ontario, Newfoundland and Prince Edward Island. Other provinces are planning vaccination programs this fall including Alberta, Quebec and British Columbia.

The Toronto, Hamilton, York and Dufferin-Peel Catholic school boards said it will offer the vaccinations to students whose parents request it. But the Halton Catholic board pulled its support for Gardasil in June.