Figure 2. A roadmap of primary pandemic prevention through spillover investigation from discovery to the prevention of zoonotic spillover. The pathway from discovery of a zoonotic pathogen in reservoir hosts to the prevention of future spillovers often begins with the detection of spillovers in persons or domestic animals. If those detections prompt One Health investigations, followed by in-depth studies to identify the root causes of spillover, the resulting knowledge can inform the design, testing and implementation of interventions to address both proximal and distal drivers of spillover risk.