Grant: Operating Grant

Provincial governments have been offering the human papillomavirus (HPV) vaccine free to young girls since 2007-2008. Although provinces have directed their HPV vaccination programs at different school grades, girls receiving this vaccine are generally much younger than those included in clinical trials. In addition, parental concerns about the vaccine's safety have proven to be an important barrier to use in some provinces, reaching a low of 50 percent in Ontario. Such low levels of uptake are of concern not only because they are detrimental to public health efforts aimed at reducing the burden of HPV-related diseases, but also because they undermine the cost-effectiveness of HPV immunization programs. Given these concerns, it is important to evaluate the safety and usage of this vaccine in the young girls being vaccinated. This study will use anonymized information from Ontario's health and immunization databases to identify over 250,000 Grade 8 girls eligible for the province's HPV immunization program between 2007 and 2010. This information will be used to evaluate the risk of serious adverse events following vaccination and assess the pattern and predictors of vaccine use. The results of this study will help young girls and their parents make informed decisions about vaccinating against HPV, and will inform policy makers regarding ways to maximize the health benefits and cost-effectiveness of HPV immunization programs.