Public health in a fracturing world: the erosion of the international rules-based order.

One of the greatest threats to public health today is not any single disease, environmental hazard, or conflict, but the erosion of the international rules-based order that enables countries to cooperate in addressing shared risks. Over the past decade, public health has faced increasingly interconnected challenges, including climate change, conflict, pollution, emerging infectious diseases, food and water insecurity, mass displacement, and misinformation. These threats are amplified by fragile governance, growing inequality, and declining trust in institutions. Public health depends fundamentally on international cooperation. Surveillance systems, outbreak reporting, vaccine supply chains, environmental regulation, and climate adaptation all require shared rules, transparency, and trust between states. As these mechanisms weaken, risks become harder to manage and their effects more unequal. Public health should adapt by strengthening collaborative infrastructure, treating misinformation as a major health threat, investing in shared preparedness, and engaging more actively with trade, finance, climate, and security policies. Rebuilding effective international cooperation is essential to protecting health in an increasingly fragmented world.