The chapter discusses the importance of ecological countermeasures in preventing pathogen spillover and subsequent pandemics. It highlights the current global focus on pandemic preparedness and response, but emphasizes the need for more attention to primary pandemic prevention, particularly the prevention of zoonotic spillover. The authors argue that pandemics often originate in ecological systems, and thus, integrating ecological approaches alongside biomedical methods is essential for a comprehensive pandemic prevention strategy. The chapter outlines the mechanisms linking environmental change and zoonotic spillover, using bats as a case study. It identifies ecological interventions that can disrupt these spillover mechanisms and proposes policy frameworks for their implementation. Key points include: 1. **Pandemic Prevention**: Reducing the risk of future pandemics requires investment in prevention, preparedness, and response. Primary pandemic prevention, which focuses on reducing the likelihood of pathogen spillover from animals to humans, has received less attention compared to secondary pandemic prevention and response. 2. **Mechanisms of Spillover**: Pandemics typically start with a microbe infecting a wild animal and then spreading to humans. This process involves several barriers, including species distribution, immune functions, human exposure, and susceptibility. 3. **Land Use-Induced Spillover**: Land-use changes can increase the risk of spillover by altering the behavior and energy levels of reservoir hosts, increasing human exposure, and facilitating the spread of pathogens. 4. **Ecological Countermeasures**: These measures aim to protect and restore wildlife habitats, reduce stress on reservoir hosts, and mitigate human-wildlife interactions. The authors propose a tiered approach that prioritizes preserving intact ecosystems, enhancing habitat integrity, and protecting critical areas for reservoir hosts. 5. **Policy and Implementation**: The chapter calls for the establishment of an Intergovernmental Panel for Pandemics to guide policy and program implementation. It also emphasizes the importance of involving local communities and Indigenous Peoples in designing and implementing ecological countermeasures. 6. **Metrics and Evidence Base**: Clear and robust metrics are needed to evaluate the effectiveness of pandemic prevention efforts. The chapter suggests integrating these metrics into existing biodiversity and climate change frameworks. 7. **One Health Approach**: The One Health approach, which focuses on the health of people, animals, and ecosystems, offers opportunities for implementing ecological countermeasures. The authors propose creating networks of ecosystem health workers to operationalize One Health and support local communities. 8. **Conclusion**: The chapter concludes that while biomedical countermeasures are crucial, ecological approaches are essential for preventing pandemics. The relevance and necessity of ecological approaches are expected to increase as challenges such as climate change and biodiversity loss intensify.The chapter discusses the importance of ecological countermeasures in preventing pathogen spillover and subsequent pandemics. It highlights the current global focus on pandemic preparedness and response, but emphasizes the need for more attention to primary pandemic prevention, particularly the prevention of zoonotic spillover. The authors argue that pandemics often originate in ecological systems, and thus, integrating ecological approaches alongside biomedical methods is essential for a comprehensive pandemic prevention strategy. The chapter outlines the mechanisms linking environmental change and zoonotic spillover, using bats as a case study. It identifies ecological interventions that can disrupt these spillover mechanisms and proposes policy frameworks for their implementation. Key points include: 1. **Pandemic Prevention**: Reducing the risk of future pandemics requires investment in prevention, preparedness, and response. Primary pandemic prevention, which focuses on reducing the likelihood of pathogen spillover from animals to humans, has received less attention compared to secondary pandemic prevention and response. 2. **Mechanisms of Spillover**: Pandemics typically start with a microbe infecting a wild animal and then spreading to humans. This process involves several barriers, including species distribution, immune functions, human exposure, and susceptibility. 3. **Land Use-Induced Spillover**: Land-use changes can increase the risk of spillover by altering the behavior and energy levels of reservoir hosts, increasing human exposure, and facilitating the spread of pathogens. 4. **Ecological Countermeasures**: These measures aim to protect and restore wildlife habitats, reduce stress on reservoir hosts, and mitigate human-wildlife interactions. The authors propose a tiered approach that prioritizes preserving intact ecosystems, enhancing habitat integrity, and protecting critical areas for reservoir hosts. 5. **Policy and Implementation**: The chapter calls for the establishment of an Intergovernmental Panel for Pandemics to guide policy and program implementation. It also emphasizes the importance of involving local communities and Indigenous Peoples in designing and implementing ecological countermeasures. 6. **Metrics and Evidence Base**: Clear and robust metrics are needed to evaluate the effectiveness of pandemic prevention efforts. The chapter suggests integrating these metrics into existing biodiversity and climate change frameworks. 7. **One Health Approach**: The One Health approach, which focuses on the health of people, animals, and ecosystems, offers opportunities for implementing ecological countermeasures. The authors propose creating networks of ecosystem health workers to operationalize One Health and support local communities. 8. **Conclusion**: The chapter concludes that while biomedical countermeasures are crucial, ecological approaches are essential for preventing pandemics. The relevance and necessity of ecological approaches are expected to increase as challenges such as climate change and biodiversity loss intensify.