The United States has completed its withdrawal from the World Health Organization: it has ceased contributions and technical participation in the activities of the UN health agency. Washington is, indeed was, by far the WHO’s main financier, contributing about 18 percent of its overall funding. The Geneva-based agency’s latest biennial budget, for 2024-25, was $6.8 billion. The news, in itself, seems distant from everyday life. But what does it really mean in practice? How does WHO impact our lives even when we don’t realize it?

To understand this, imagine we are in the initial stages of an epidemic destined to become a pandemic. More than imagining it, in reality, we have already experienced it in 2020, even if many seem to have forgotten it. Let’s try to build a scenario anyway. A woman arrives in a small hospital in Africa with atypical pneumonia for which the usual tests give no answers. After many similar cases that decimate a village, an epidemiologist who works in a more equipped laboratory in a large city enters the scene. He collects clinical data, analyzes the samples and realizes that he is faced with an unknown pathogen that causes the so-called “disease X”.

Out on a limb

In a world where the WHO is functioning at full capacity, the researcher uploads that data to a global surveillance network and, within hours, sees similar cases appear on other continents. Also from the United States, which historically is not only among the major financiers of the WHO but also one of the largest producers of clinical, epidemiological and genetic data; at least until January 26, 2026.

If the United States is no longer part of the WHO, that flow stops. US data no longer automatically enters the system, and for researchers, it’s like looking at a map with part of the world covered: they know something is happening down there, but they can’t measure it in real time. Even if a US researcher is studying that same virus, his work will no longer feed into a shared global assessment. There is no recognized center that collects all the information, compares it and clearly says: “This is the direction the virus is taking.”

National and not global responses

When a new pathogen emerges, the WHO is not just an observer: it coordinates a global surveillance network, connects the control centers of the various countries, encourages comparison between the laboratories that sequence the genome of the virus and provides shared indications on how to track infections and contain the spread.

Let’s imagine that the virus that causes disease X arrives in European hospitals. During Covid, despite all the limitations and errors, a common reference existed. If no organization puts all these pieces together and says what to do, the healthcare worker faced with a patient still has to make a decision knowing that he has a fragmented picture. And in the world of research there is no individual talent that can replace the systematic sharing of data. With the United States outside the WHO, it is possible that it will adopt different or even opposite health standards compared to international recommendations. At the same time, the countries that continue to follow the WHO will do so without having full access to the technical tools and information that came from the United States.

This does not mean that American science will cease to exist, but that it will become more difficult to integrate it into a global response. One of the aspects, often invisible, concerns the trained people who work. The United States has provided experts, managers and technical leaders within the WHO for decades. With their withdrawal, the organization loses some of its scientific leadership.

The consequences become even more concrete when it comes to drugs and vaccines. Once a pathogen, such as a virus, is identified, pharmaceutical companies begin working on a vaccine almost immediately. To do this effectively, however, we need a complete picture of the circulating variants. If a variant arises and spreads in the United States, that data could arrive late or piecemeal, and the vaccine would risk being less precise. Traditionally, the WHO organizes groups of international experts, compares data from laboratories around the world and defines a reference sequence of the virus that becomes the basis for designing vaccines.

Life support for health crises

In January 2025, the sixth case of mpox was announced in the UK within a few months in East Sussex. Mpox, formerly called “monkeypox,” is a zoonotic viral disease. In the same weeks, new cases were also reported in France, Germany, Belgium, Sweden, Canada and the United States, demonstrating how the virus was spreading outside of Africa. Also in January 2025, the president of Tanzania confirmed an outbreak of Marburg, a virus similar to Ebola, after the country’s health minister initially denied its existence. The confirmation came only following independent reporting by the World Health Organization (WHO), which had reported nine suspected cases and eight deaths.

These two episodes, which occurred thousands of kilometers away from each other, clearly highlight why, if the World Health Organization did not exist, it would be necessary to create it: to promptly identify global health threats and prevent the spread of infectious diseases around the world.