Reported August 02, 2007

OTTAWA (Reuters) - Canada's biggest province will begin vaccinating Grade 8 girls against cervical cancer this fall, the Ontario government said on Thursday, but some medical experts say the campaign is premature and could lead to more unsafe sex.

The Ontario provincial government will offer the vaccine against human papilloma virus (HPV), a cause of cervical cancer, on a voluntary basis to 84,000 school girls aged 13 and 14.

The assumption is that age group has not yet been exposed to the viruses that cause the sexually-transmitted disease.

"We're providing this vaccine to women at a young age so we can help prevent the spread of HPV and save lives," Ontario Premier Dalton McGuinty said in a statement.

About 400 Canadian women die from cervical cancer every year, 140 of them in Ontario. It is the second most common cancer in women aged 20 to 44, after breast cancer.

But the vaccine launch was clouded by concerns by some doctors who said more independent study is needed on the effectiveness of the Gardasil vaccine and on the implications for teenage sexual behavior.

In a commentary published online in the Canadian Medical Association Journal on Wednesday, a group of experts pointed out that the reported vaccine trials of Gardasil, manufactured by Merck Frosst Canada, have been funded wholly, or in part, by the manufacturer.

"A careful review of the literature ... reveals a sufficient number of unanswered questions to lead us to conclude that a universal immunization program aimed at girls and women in Canada is, at this time, premature and could possibly have unintended negative consequences for individuals and for society as a whole," said Abby Lippman, an epidemiologist at McGill University in Montreal and lead author of the commentary.

Lippman said there is no urgency for a massive vaccination in Canada, where deaths from cervical cancer have been declining. More needs to be known about the vaccine, including the duration of immunological protection it provides and whether factors such as smoking or poor health influence its effectiveness, she said.

Without a public education campaign, misunderstandings about the vaccine could lead teenagers to practice unsafe sex, Lippman says.

"Might misunderstandings about what the vaccine does and does not do lead to reductions in safer sex practices and Pap screening rates? These are among the questions raised ... and they remain pertinent and unanswered," the article said.

The vaccine program is funded by the federal government and will eventually be implemented by all the provinces, which make their own rules about how to administer it.

The government approved the vaccine in July 2006 to protect against two types of HPV that are responsible for about 70 percent of cervical cancer cases in Canada.