HPV vaccine, riskier sexual activity not linked, Canadian researchers say

There are concerns the vaccine, which guards against four types of the HPV shown to cause cervical cancer and anogenital warts, may give girls a false sense of security about contracting sexually transmitted infections (STIs) and lead them to engage in riskier sexual activity.

"These findings suggest fears of increased risky sexual behaviour following HPV vaccination are unwarranted and should not be a barrier to vaccinating at a young age," says Dr. Smith, the lead author on the study that was published in the Canadian Medical Association Journal.

This study looked at a cohort of 260,493 girls, of whom about half (128,712) were eligible for Ontario's publicly funded, school-based HPV vaccination program during the first two school years it was offered (2007-08 and 2008-09). The researchers followed the girls until March 31 of their Grade 12 year. About six per cent of girls became pregnant or contracted an STI between Grades 10 and 12, with 10,187 pregnancies and 6,259 cases of non-HPV-related sexually transmitted infections.

"Neither HPV vaccination nor program eligibility increased the risk of pregnancy nor non-HPV-related STIs among females aged 14-17 years," says Dr. Lévesque, the senior author of the study. "The results of this study can be used by physicians, public-health providers and policy-makers to address public and parental concerns about HPV vaccination and promiscuity."

Since 2006, the HPV vaccine has been licensed in almost 100 countries, including Canada. Many of these countries have national HPV vaccination programs to protect young girls against the virus before they become sexually active.