Nancy E. Messonnier, MD is director of the National Center for Immunization and Respiratory Diseases (NCIRD) at the Centers for Disease Control and Prevention (CDC) and leads the CDC’s efforts on COVID-19 vaccination. She joins JAMA’s Q&A series to discuss the agency’s response to emerging coronavirus variants, the FDA advisory hearings on the new Johnson & Johnson vaccine, and other agency activities and priorities related to COVID-19 control.