The World Health Organization (WHO) is a United Nations specialized agency and the largest intergovernmental health institution, headquartered in Geneva, Switzerland. Its objective, defined in Article 1 of its Constitution, is "the attainment by all peoples of the highest possible level of health". The Constitution, signed on July 22, 1946, and entering into force on April 7, 1948, was created in the aftermath of World War II to coordinate international public health efforts. It solved the problem of fragmented global health governance by incorporating the duties of previous bodies like the League of Nations' Health Organization.
The mechanism of the WHO is governed by the World Health Assembly (WHA), which is the decision-making body composed of its 194 Member States. The WHA has the authority to adopt regulations concerning sanitary and quarantine requirements and standards for biological products. Article 2 of the Constitution outlines its functions, which include acting as the directing and coordinating authority on international health work. The WHO is connected to the broader United Nations (UN) system, established under Article 57 of the UN Charter.
A key mechanism it connects to is the International Health Regulations (IHR), which guide 196 States Parties on public health risks. The IHR were amended in 2024 by the Seventy-seventh World Health Assembly, introducing a new global alert level called a "pandemic emergency". This amendment, driven by lessons from the COVID-19 pandemic, strengthens access to medical products. Furthermore, the WHO Pandemic Agreement, a new legally binding international instrument, was adopted by the WHA on May 20, 2025, to strengthen global preparedness and response.