Grant: Operating Grant

In 2007, provinces began implementing human papillomavirus (HPV) vaccination programs for young girls in an effort to reduce the occurrence of genital warts and cervical cancer. Although there was a great deal of hype about these programs, there was also controversy over the many unanswered questions about the real-world effects of the HPV vaccine in this young population. Even now, more than five years after the programs began, the controversy continues. This study is based in Ontario, where the HPV vaccine has been offered free-of-charge to all Grade 8 girls since September 2007. The study will include all girls in Grade 8 in 2007/08-2010/11 (eligible for free vaccination) and 2003/2004-2006/2007 (ineligible for free vaccination). We will create a similar cohort of Grade 8 boys. Data for this study will come entirely from the province's administrative health and immunization databases, which contain secure, anonymous information on all individuals covered under Ontario's Health Insurance Plan. Using this information, we will answer questions of particular public interest - for example: (1) To what extent does vaccinating girls in Grade 8 girls reduce their risk of getting genital warts? (2) Has HPV vaccination led to an increase in teen pregnancies or sexually transmitted infections (excluding warts)? and (3) Does vaccinating girls decrease the occurrence of genital warts in boys? To ensure the accuracy of our results, we will also be undertaking a re-abstraction study to validate our outcome definitions. The results of our study will help young girls and their parents make more educated decisions about HPV vaccination. The results will also provide information that policy decision makers can use for strengthening HPV vaccination programs.