Across the United States, school districts are grappling with questions of whether and how to reopen and keep open elementary and secondary schools in the 2020-21 academic year. Using household data from before the pandemic (2014-17), we examined how often people who have health conditions placing them at risk for severe coronavirus disease 2019 (COVID-19) were connected to schools, either as employees or by living in the same households as school employees or school-age children. Between 42.0 percent and 51.4 percent of all school employees met the Centers for Disease Control and Prevention's (CDC's) definition of having or potentially having increased risk for severe COVID-19. Among all adults with CDC-defined risk factors for severe COVID-19, between 33.9 million and 44.2 million had direct or within-household connections to schools.