Over the course of the COVID-19 pandemic, the US has seen a dramatic shift in the routines of daily life as we have worked to reduce transmission. One of the most dramatic shifts has been the reduction or elimination of in-person learning in many high schools, a change that may have influenced the spread of STIs among adolescents. School closures may have resulted in a decline in sexual contacts and thereby a reduction in the spread of STI, or conversely, may have provided an opportunity for social interactions to move to less regulated spaces where earlier or more frequent sexual contact may occur, thereby increasing STI transmission. This project will use two waves of the Youth Risk Behavior Survey (YRBS) and STI surveillance data to quantify the relationship between school closures and changes in sexual behavior among high school students or STI incidence, and possible unintended consequences of school closures.