What is One Health? One Health is an interdisciplinary framework that aims to sustainably advance and safeguard the health of humans, animals, and the environment (Figure 1). At its core, the One Health approach emphasises that the health of people is inextricably linked to that of ecosystems and the species inhabiting them. Through this lens, One Health extends from environmental health to address contemporary health challenges, which is especially relevant given the recent global spread of H5N1 influenza and COVID-19, the rise of antibiotic resistance, and increasing frequency and magnitude of harmful algal blooms. Because One Health inherently brings together all aspects of public health, collaboration among professionals from various domains — including medicine, veterinary science, and environmental science — is essential for effectively managing and preventing health risks.