On April 8, 2026, at the International Agency for Research on Cancer (IARC) in Lyon, Institut Mérieux, in partnership with emlyon business school, brought together scientists, economists, public health leaders and private sector representatives around a question that sounds simple but has proved remarkably difficult to answer: if human, animal and environmental health are inseparable, why do our systems continue to treat them separately?
One health, one medicine: an old idea whose time has come
The One Health approach is often presented as a new paradigm. It is not.
Yet as Alain Mérieux recalled in his opening remarks, Louis Pasteur had already underlined the fundamental unity of human and animal medicine, encompassing diagnostics, serotherapy and vaccination. What has changed is the scale of the threats (pandemics, antimicrobial resistance, biodiversity collapse) and the urgency to act, at a time when institutions are still struggling to adapt.
The conference took place in the closing days of the One Health Summit, hosted by France as part of its G7 Presidency. IARC Director Dr Elisabete Weiderpass recalled in her welcoming address that cancer prevention falls squarely within the One Health framework: environmental carcinogens, zoonotic agents and occupational exposures all call for cross-cutting thinking.
The day before, some twenty organizations had signed a Global One Health Diagnostic Access Compact, committing to place diagnostics at the foundation of every health response. “Without diagnostics, medicine is blind,” said Alain Mérieux.
That Compact, coupled with Institut Mérieux’s recent acquisition of a stake in Ceva Santé Animale, reflects a determination to bring human and veterinary health under the same banner, in keeping with the Pasteurian legacy.
From vision to action: closing the structural gap
The panel, moderated by Vanina Laurent-Ledru, Director of Public Health at Institut Mérieux, explored a two-sided diagnosis: political momentum around One Health has never been stronger (a G7 meeting on the subject would have been unthinkable a few years ago), yet that very momentum carries a risk. Ramanan Laxminarayan, President of the One Health Trust and researcher at Princeton, drew a parallel with universal health coverage, an agenda weakened by its own breadth: by trying to encompass everything, it ended up delivering too little. To avoid that trap, One Health needs clear, concrete metrics: How many lives saved? How many hospitalizations averted?
The numbers speak for themselves. 90% of the planet’s mammalian biomass now consists of humans and livestock. The remaining 10% accounts for all wild mammals. That single figure makes animal health a matter of collective security, not just a specialist concern. At the same time, the global response is profoundly unequal. Dr Ngashi Ngongo of Africa CDC noted that in 2022, roughly one million AMR-associated deaths were recorded on the African continent, against an investment of about $200 million. That same year, 600,000 HIV-related deaths mobilized $11.8 billion. The gap says a great deal about how we choose to see, or not see, certain threats.
Nobel laureate Jean Tirole, from the Toulouse School of Economics, went to the root of the problem. Antimicrobial resistance, he explained, is structurally identical to climate change: an externality that crosses borders, generations and sectors. And like climate, it rests on a pricing failure. Antibiotics are too cheap. Just as underpriced carbon emissions fuel pollution, underpriced antibiotics fuel misuse and discourage innovation. Thirty-four years of climate advocacy have shown that raising awareness alone does not change behavior. Economic incentives do.
From the field: what works, what is missing
The second half of the discussion moved from diagnosis to practice, and the most impactful contributions came from those working closest to the ground.
Dr Jarbas Barbosa da Silva Jr, Executive Director of the Pan American Health Organization (PAHO), stressed that One Health is not preparation for a future crisis but an immediate necessity.
Avian influenza outbreaks in the Americas, with spillover to mammals and confirmed human cases, cannot be managed without integrated surveillance. Sylvatic yellow fever, whose urban form was eliminated in 1942, still requires real-time animal and environmental monitoring. PAHO’s regional procurement mechanism, in operation for 42 years and accounting for $1 billion in products procured last year, is a proven model. But it also makes an essential point: operational One Health rests on institutional architecture built over decades, not proclaimed at summits.
Marc Prikazsky, CEO of Ceva Santé Animale, put plain figures on the table. 70% of new human infections originate in animals. Vaccinating livestock against salmonella, Q fever or avian influenza costs 20 to 25 times less than treating the consequences in humans. Yet the equation breaks down as soon as the health cost falls on human systems while the intervention must take place on the animal side. Rabies is the clearest case: 60,000 deaths a year, many of them children, with solutions that exist but no viable market to fund them. Marc Prikazsky also described Ceva’s work with the CNRS in Antarctica, where vaccines are being tested on royal penguins and sea lions to curb the damage caused by avian influenza spreading to wildlife.
Dr Ngongo traced the trajectory of mpox across the African continent: 14 countries affected when Africa CDC declared a continental health emergency in August 2024, 33 by the time it was lifted in January 2026. The lesson is clear: underinvestment upstream costs far more downstream. He also raised the question of equity within One Health itself. Human health captures most of the attention and resources, animal health less so, environmental health almost none. “We cannot leave orphans in the family.”
Beyond declarations: solutions and commitments
This was a stated aim from the outset: to move beyond analysis and propose concrete actions. Bruno Lina, President of Université Claude Bernard Lyon 1 and a central figure in France’s COVID response, drew on the pandemic experience. The bottleneck was not knowledge but capacity: going from a few dozen PCR tests a day to several thousand, securing reagents, building sequencing infrastructure. These resources need to exist before a crisis, not be assembled in the heat of one. Bruno Lina also made the case for a less anthropocentric reading of One Health. Vaccinating horses eliminated the Hendra virus threat. Vaccinating animals eradicates rabies. Restoring ecosystems reduces the emergence of new pathogens. “If we’re talking about One Health, it cannot be anthropocentric.”
On the economic front, Jean Tirole presented a mechanism that could help unlock antibiotic innovation: transferable patent extension vouchers, currently under consideration by the European Commission and Parliament. His research shows that, perhaps surprisingly, these vouchers cost public health systems less than direct cash prizes, particularly where generic competition is weak. Five are planned over the next fifteen years in Europe. Not a complete solution, he noted, but a real shift in a field where the pipeline is all but empty.
The panel closed with concrete commitments. Marc Prikazsky announced a field trial to demonstrate that rabies can be controlled through targeted animal vaccination. PAHO launched PIVOT (Preventing Infections through Vigilance at the Origin of Transmission), a twelve-month initiative to map and strengthen One Health capacities across the Americas, with FAO and the World Bank. Africa CDC confirmed its priority on accelerating access to diagnostics, antibiotics and vaccines, including a continental procurement mechanism and a high-level AMR meeting in June in Nigeria. Ramanan Laxminarayan called for a Gavi equivalent dedicated to animal vaccines, noting that coverage gaps between the poorest and richest countries often reach 99% to zero, far wider than what existed for human vaccines when Gavi was created.
To close, Bruno Versaevel of emlyon business school highlighted the role of Lyon’s health innovation ecosystem: the Mérieux Foundation’s GABRIEL network (22 research laboratories worldwide), the recently created Infectious Diseases Cluster, and local startups working on health data interoperability. Summing up the morning, he concluded: “The science is there. What remains to be built are the systems, incentives and political will to put it to work.”
Watch the full conference replay: