The COVID-19 pandemic has upended our societies and re-shaped the way we go about our day-to-day lives—from how we work and interact to the way we buy groceries and attend school. In this talk, I will present a series of studies exploring how our behavior, mobility patterns, and social networks have altered and been altered by COVID-19. Leveraging global data sets that represent billions of people, I will show how myriad factors interacted to shape the course of the pandemic. Using the lessons learned from COVID-19, I will discuss how we might balance the ethical and privacy considerations around high-resolution mobility data with their critical role in responding to epidemics.