Redefining human health, a crucial step in the “One Health” approach

Expert view 20 May 2025
In an article published today in The Lancet, experts are calling for changes to the definition of health. This definition needs to include the characteristics and values associated with the “One Health” concept. Explanations with Thierry Lefrançois, lead author of the article, member of COVARS and advisor to the CEO of ϲͼ.
Thierry Lefrançois against a backdrop of intense air pollution in the megalopolis of Jakarta, Indonesia (photomontage) © ϲͼ, F. Dunouau, A. Rival
Thierry Lefrançois against a backdrop of intense air pollution in the megalopolis of Jakarta, Indonesia (photomontage) © ϲͼ, F. Dunouau, A. Rival

Thierry Lefrançois against a backdrop of intense air pollution in the megalopolis of Jakarta, Indonesia (photomontage) © ϲͼ, F. Dunouau, A. Rival

Key points

  • Leading experts are calling for a revision of the definition of health to better address current challenges
  • This revision is the starting point for political and economic changes and actions

Redefining what we mean by human health – this is the call made in an article published today in The Lancet, as the WHO assembly gets underway and this global institution faces the need to reinvent itself following the withdrawal of the United States. The goal is to better reflect the characteristics and values associated with the “One Health” approach and the current determinants of health.

The current definition of health dates back to 1948: health is a state of complete physical, mental and social well-being, and not merely the absence of disease or infirmity. At the time, this was relatively innovative, but since then, the challenges and context have changed considerably”, explains Thierry Lefrançois, a veterinarian at ϲͼ and member of COVARS.

Human health must adapt to a changing global context, which affects the determinants of health (pollution, population ageing, globalisation, and so on.). It needs to be understood in a fundamentally holistic way, as inseparable from climate, environment, biodiversity, agriculture and food systems, in order to create co-benefits for humans, animals, plants and ecosystems.

Expanding the definition of human health is a crucial step towards moving from a human-centred view of health to a holistic approach to health for the planet and its people, driven by humans.

Changing the definition of human health should be the starting point for political and economic changes and actions aimed at:

  • increasing action and financing for prevention, based on the current determinants of health;
  • revising the World Trade Organization rules to include environmental and health costs (negative externalities) in products and trade;
  • promoting national-level changes towards interministerial governance of the living world;
  • and developing health research projects and initiatives at the interface between science and policy at all levels.

Developing a new definition of health will be a long, multi-stakeholder process involving the full quadripartite (WHO, the Food and Agriculture Organization of the United Nations, the World Organisation for Animal Health, and the United Nations Environment Programme), as well as intergovernmental platforms such as IPBES (the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services).

The new definition of health will also need to reflect political determinants, which have a major impact on health today. There can be no health without peace.

The co-authors of this article are all experts in human, animal and environmental health, working at the science-policy interface: Thierry Lefrançois, Member of COVARS and “One Health” Advisor  to the CEO of ϲͼ; Jean-François Delfraissy, Chair of the think tank Santé Mondiale 2030; Brigitte Autran, Emeritus Professor at La Sorbonne; and David Obura, Chair of IPBES.