There is no evidence to suggest that getting an HPV vaccination encourages teenage girls to engage in riskier sexual behaviour, according to a new study.

The study, published Monday in the Canadian Medical Association Journal, used data from the B.C. Adolescent Health Survey, which collects health information every five years from B.C. students in grades 7 through 12. The study is based on responses from almost 300,000 female students provided in the years 2003, 2008 and 2013.

The HPV vaccine was made available in 2008 to girls in Grade 6 in B.C. schools, according to Elizabeth Saewyc, director of the school of nursing at the University of British Columbia and one of the study's authors.

Saewyc said the study was done in part to address concerns that the vaccine gives girls the false sense that they can engage in riskier sexual behaviour. She found the opposite to be true.

According to the data, the number of girls who reported having sex between ages 12 and 18 decreased to 18 per cent in 2013 from 21 per cent in 2003. And among those girls who are sexually active, oral contraceptive use increased by 9 per cent and teenage pregnancy decreased by 42 per cent in that 10-year period.

Teenage girls' sexual behavior remained the same or became safer after HPV vaccination was introduced in BC schools, according to new research: <a href="https://t.co/0G2pL3Q8qH">https://t.co/0G2pL3Q8qH</a><a href="https://twitter.com/HPV_research?ref_src=twsrc%5Etfw">@HPV_research</a> <a href="https://twitter.com/hashtag/cdnhealth?src=hash&ref_src=twsrc%5Etfw">#cdnhealth</a> <a href="https://twitter.com/hashtag/publichealth?src=hash&ref_src=twsrc%5Etfw">#publichealth</a> <a href="https://twitter.com/hashtag/HPVvaccine?src=hash&ref_src=twsrc%5Etfw">#HPVvaccine</a> <a href="https://t.co/jy10UKIqWf">pic.twitter.com/jy10UKIqWf</a> —@CMAJ

"We can say for sure that the HPV vaccine did not increase risky behaviours among adolescents," said Saewyc.

"In fact, young people are making healthier decisions today than they ever have."

Saewyc acknowledged there are other factors that may be contributing to teens' healthier choices, such as wider access to information on the internet and better sexual health information than there was over a decade ago.

"We can't actually connect those dots … but we can say the trends look like they are going to continue," said Saewyc.

It's not known why girls seemed to be making healthier sexual choices after the implementation of the HPV vaccination program, but it's possible that doctors throw in some education about sex when giving the vaccine, said Susan Rosenthal, director of the Division of Child and Adolescent Health at NewYork-Presbyterian/ Columbia University Irving Medical Centre in New York City.

"There's been pretty consistent evidence from the U.S. that when you provide information about contraception and condoms, teens reduce sexual risk-taking, delay sexual initiation and when they do have sex, they use protection," Rosenthal said.

Vaccination time can be a good opportunity to start a conversation, Rosenthal said. "A lot of times parents and others don't know how to bring the subject up," she added. "The HPV vaccination potentially provides you an opening and an opportunity to have a sex education conversation with families."

In 2013, 69 per cent of female students in Grade 6 were vaccinated as part of B.C.'s school-based vaccination program. The province expanded the program to include male students in 2017.

The study focused solely on heterosexual female students because, according to Saewyc, that was the most representative data available in B.C. with a large number of adolescent girls.

With files from Reuters

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