The article discusses the need for ecological countermeasures to prevent zoonotic spillover and subsequent pandemics. It emphasizes that while preparedness and response to pandemics have received significant attention, prevention—especially reducing the risk of zoonotic spillover—has been largely overlooked. The article outlines the mechanisms linking environmental change and zoonotic spillover, using the spillover of viruses from bats as a case study. It identifies ecological interventions that can disrupt these spillover mechanisms and proposes policy frameworks for their implementation. The article argues that pandemics originate in ecological systems and advocates for integrating ecological approaches alongside biomedical approaches in a comprehensive and balanced pandemic prevention strategy. The article highlights that reducing the risk of future pandemics requires investment in prevention, preparedness, and response. Currently, most attention and funding are allocated to mitigation after a pathogen is already circulating in humans, prioritizing outbreak detection and medical countermeasures. By contrast, primary pandemic prevention—defined as reducing the likelihood a pathogen transmits from its animal host into humans (zoonotic spillover)—has received less attention in global conversations, policy guidance, and practice. The article argues that investing in pandemic prevention is essential to achieve efficient, equitable, and cost-effective protection from disease. The article identifies two key points for effective pandemic prevention: first, that pandemics almost always start with a microbe infecting a wild animal in a natural environment, and second, that human-caused land-use change often triggers the events that facilitate spillover of microbes from wild animals to humans. As land-use change becomes more intense and extensive, the risk of zoonotic spillovers, and subsequent epidemics and pandemics, will increase. Designing land management and conservation strategies to explicitly limit spillover is central to meeting the challenge of pandemic prevention at a global scale. The article presents a roadmap for reducing pathogen transmission from wildlife to humans and other animals. It shows how strategic conservation and restoration of nature for reservoir hosts, and mitigation of risks for humans most at risk—what we define as ecological countermeasures—can prevent spillover and protect human and animal health, while also addressing key drivers of climate change and biodiversity loss. The article discusses the mechanisms of spillover, highlighting that despite hundreds of thousands of potentially zoonotic microbes circulating in nature, pandemics are rare. Microbes must overcome a series of barriers to transmit from a wild animal to a human. These barriers include the distribution of the species that maintains the zoonotic pathogen in nature, the immune functions within wildlife hosts, human exposure, susceptibility, and amplification within the new host. The article also discusses land use-induced spillover, emphasizing that intact ecosystems provide the first line of defense against new pandemics. Land-use changes and other environmental disturbances erode these first three barriers to spillover by changing the reservoir hosts' spatial behavior and allostatic load, as well as alteringThe article discusses the need for ecological countermeasures to prevent zoonotic spillover and subsequent pandemics. It emphasizes that while preparedness and response to pandemics have received significant attention, prevention—especially reducing the risk of zoonotic spillover—has been largely overlooked. The article outlines the mechanisms linking environmental change and zoonotic spillover, using the spillover of viruses from bats as a case study. It identifies ecological interventions that can disrupt these spillover mechanisms and proposes policy frameworks for their implementation. The article argues that pandemics originate in ecological systems and advocates for integrating ecological approaches alongside biomedical approaches in a comprehensive and balanced pandemic prevention strategy. The article highlights that reducing the risk of future pandemics requires investment in prevention, preparedness, and response. Currently, most attention and funding are allocated to mitigation after a pathogen is already circulating in humans, prioritizing outbreak detection and medical countermeasures. By contrast, primary pandemic prevention—defined as reducing the likelihood a pathogen transmits from its animal host into humans (zoonotic spillover)—has received less attention in global conversations, policy guidance, and practice. The article argues that investing in pandemic prevention is essential to achieve efficient, equitable, and cost-effective protection from disease. The article identifies two key points for effective pandemic prevention: first, that pandemics almost always start with a microbe infecting a wild animal in a natural environment, and second, that human-caused land-use change often triggers the events that facilitate spillover of microbes from wild animals to humans. As land-use change becomes more intense and extensive, the risk of zoonotic spillovers, and subsequent epidemics and pandemics, will increase. Designing land management and conservation strategies to explicitly limit spillover is central to meeting the challenge of pandemic prevention at a global scale. The article presents a roadmap for reducing pathogen transmission from wildlife to humans and other animals. It shows how strategic conservation and restoration of nature for reservoir hosts, and mitigation of risks for humans most at risk—what we define as ecological countermeasures—can prevent spillover and protect human and animal health, while also addressing key drivers of climate change and biodiversity loss. The article discusses the mechanisms of spillover, highlighting that despite hundreds of thousands of potentially zoonotic microbes circulating in nature, pandemics are rare. Microbes must overcome a series of barriers to transmit from a wild animal to a human. These barriers include the distribution of the species that maintains the zoonotic pathogen in nature, the immune functions within wildlife hosts, human exposure, susceptibility, and amplification within the new host. The article also discusses land use-induced spillover, emphasizing that intact ecosystems provide the first line of defense against new pandemics. Land-use changes and other environmental disturbances erode these first three barriers to spillover by changing the reservoir hosts' spatial behavior and allostatic load, as well as altering