Bird Flu Mutation Risk Could Trigger Deadlier Pandemic, Scientists Warn

Growing alarm over bird flu mutation risk has scientists warning that the next global pandemic could be sparked by the H5N1 avian influenza virus. Experts caution that the highly pathogenic bird flu, which has been spreading widely among wild birds, poultry, and even some mammals, might trigger a pandemic worse than COVID-19 if it mutates to spread easily between humans. France’s Institut Pasteur, one of the world’s leading infectious disease centers, recently told Reuters that such a scenario, while not inevitable, is a real risk that governments must prepare for now.

A Virus With a History of Surprises

The H5N1 strain of avian influenza — commonly called bird flu — has already led to the culling of hundreds of millions of birds in recent years, disrupting food supplies and driving up poultry prices worldwide. Since it first emerged in the late 1990s, H5N1 has become endemic in bird populations across Asia, Europe, Africa and, more recently, North and South America. Avian influenza primarily infects birds, but it can occasionally jump into mammals and humans, usually after close contact with infected poultry or contaminated environments.

According to the World Health Organization (WHO), nearly 1,000 human cases of different avian influenza A (H5) strains were reported globally from 2003 to 2025, with approximately 48% of those cases proving fatal. Most infections have been linked to direct exposure to sick or dead birds rather than human-to-human spread. However, health agencies consider bird flu a “zoonotic threat” — a virus in animals with the potential to adapt and spread among people if key mutations occur.

The European Centre for Disease Prevention and Control (ECDC) notes that outbreaks of H5N1 and related H5 viruses have intensified since 2020, with large numbers of wild birds and poultry affected across Europe. The virus has also spilled into several mammal species, including foxes, sea lions, mink and domestic cats. Each new host increases the opportunities for the virus to evolve. At the same time, countries are still dealing with other major health burdens like diabetes, hypertension and heart disease, as highlighted in GSN’s coverage of World Diabetes Day: Rising Cases. A pandemic layered on top of those existing pressures could have enormous consequences for health systems.

No Antibodies Against H5 Bird Flu

Human infections with H5N1 bird flu remain rare so far. However, scientists like Dr. Marie-Anne Rameix-Welti, medical director at France’s Institut Pasteur respiratory infections center, are deeply concerned about what could happen if the virus adapts to humans. “What we fear is the virus adapting to mammals, and particularly to humans, becoming capable of human-to-human transmission, and that virus would be a pandemic virus,” Rameix-Welti warned in a recent interview with Reuters.

The Institut Pasteur, renowned for its role in developing early COVID-19 tests, is closely monitoring avian flu viruses for any signs of adaptation. Researchers note that people have antibodies against common seasonal flu subtypes (like H1 or H3), but none against H5 avian flu strains. In other words, our immune systems would face a completely novel virus — similar to the situation at the start of COVID-19 but with a virus that historically has a much higher fatality rate in humans.

Unlike COVID-19, which tended to hit hardest among the elderly or those with pre-existing conditions, an H5N1 bird flu pandemic could seriously affect healthy individuals of all ages, including children. “A bird flu pandemic would probably be quite severe, potentially even more severe than the pandemic we experienced,” Rameix-Welti explained, underscoring the threat. Past clusters of avian influenza in humans have included previously healthy adults and children who developed rapidly progressive pneumonia and multi-organ failure.

Over the past two decades there have been numerous isolated cases of humans catching H5 bird flu (usually from close contact with infected birds). In fact, H5N1 is now so widespread that it has appeared in unexpected species — it’s been found not only in birds but also in mammals like foxes, sea lions, mink, cats, and even dairy cattle in the U.S. Recently, the first-ever human case of H5N5 (a related bird flu subtype) was recorded in Washington state, and the patient sadly died of the infection. For scientists, this case is not just a tragedy but also a warning sign that H5 viruses are continuing to diversify and probe the boundaries of species barriers.

Human Pandemic Risk Still Low — But Not Zero

Despite these worrying developments, experts say the risk of a human-to-human bird flu pandemic remains low at present. Gregorio Torres, head of the Science Department at the World Organisation for Animal Health (WOAH), emphasizes that people should not panic. “We need to be prepared to respond early enough. But for the time being, you can happily walk in the forest, eat chicken and eggs and enjoy your life. The pandemic risk is a possibility. But in terms of probability, it’s still very low,” Torres said in a statement, highlighting that as of now the virus does not readily jump between humans.

Health authorities worldwide are nonetheless urging preparedness. Dr. Rameix-Welti pointed out that, if H5N1 does gain the ability to spread among humans, the world is better prepared now than before COVID-19. “The positive point with flu, compared to COVID, is we have specific preventative measures in place. We have vaccine candidates ready and know how to manufacture a vaccine quickly,” she noted. Global vaccine makers have developed prototype H5N1 vaccines that could be mass-produced if needed. Additionally, many countries maintain stockpiles of antiviral drugs effective against influenza, which could help mitigate an outbreak in the early months while vaccines are being rolled out.

According to WHO, global laboratory and surveillance networks have also been strengthened since COVID-19, enabling faster genetic sequencing and reporting of unusual flu outbreaks. However, experts warn that surveillance remains uneven, especially in low- and middle-income countries where veterinary and public health systems may be under-resourced. That is why international bodies like WHO, ECDC and WOAH are urging governments to invest now in stronger “One Health” systems that track diseases in animals, humans and the environment together.

Why Scientists Are So Worried About Mutation

Why are scientists so concerned, given that H5N1 hasn’t yet caused sustained human outbreaks? One reason is the virus’s unprecedented behavior in animals. H5N1 has spread across continents and into a wide range of mammalian species, something earlier bird flu strains rarely did. In late 2022, a target bird flu outbreak at a mink farm in Spain provided the strongest evidence yet that H5N1 can spread between mammals. Dozens of mink became infected and the virus likely went mink-to-mink — a deeply troubling scenario, since it suggests the virus can adapt to new hosts. (Fortunately, the farm workers, who were wearing masks due to COVID precautions, were not infected.) As bird flu hits more varied animals, the fear is that the virus could evolve in ways that make human-to-human transmission easier, potentially triggering a pandemic.

Scientists are also uncovering biological reasons for H5N1’s pandemic potential. In a study published in the journal Science by researchers at the University of Cambridge and University of Glasgow, it was found that avian flu viruses can replicate at the high body temperatures caused by fever — a condition that usually helps humans fight off flu infections. Human-adapted flu viruses are typically stopped by fever, but these bird flu viruses were target to withstand fever and continue replicating. The research pinpointed a viral gene (PB1) as a key factor: when bird flu viruses swap genes with human flu viruses (a process called reassortment), an avian-derived PB1 gene can make the hybrid virus much more heat-resistant. This insight helps explain why avian influenza can cause such severe illness in people — and why a mutated bird flu could potentially spread efficiently even in the face of our natural defenses.

Another cause for vigilance is the virus’s ability to constantly evolve into new strains. The emergence of the H5N5 subtype in a human patient is a reminder that H5N1 can mix with other influenza viruses and create novel variants. While virologists say H5N5 doesn’t appear to pose a greater threat than H5N1 at this time, the fact that a new strain made the leap to a person underscores the unpredictable nature of influenza viruses. It’s a moving target that experts are tracking closely, using both traditional epidemiology and advanced tools like AI-driven “world models” to simulate how a new strain could spread. (GSN recently explored this in detail in AI World Models: The Next Big Leap in Intelligent Machines.)

In summary, the bird flu mutation risk is taken very seriously by the scientific community. The consensus is that while H5N1 is not currently spreading among people in any sustained way, its continued circulation and evolution in animal populations present a genuine pandemic threat. The world’s health agencies and researchers are on high alert — increasing surveillance of outbreaks, preparing vaccines, and educating the public — to ensure that if the virus does begin to spread in humans, it can be swiftly identified and contained. As of now, the risk to the general public remains low, but the window of opportunity to bolster pandemic preparedness is now, before H5N1 or a similar strain might acquire the ability to spread like a human flu.

Reactions From Health Authorities and Governments

Government agencies and health organizations worldwide are taking the warnings seriously. In Europe, officials are accelerating bird flu vaccination trials for poultry and strengthening farm biosecurity. France, for example, has placed its poultry sector on high alert and is preparing large-scale vaccination campaigns after suffering devastating outbreaks in recent seasons. The ECDC regularly publishes situation updates on avian influenza, urging member states to step up surveillance in birds and in people exposed to poultry.

The United States government, through the CDC and the Department of Agriculture, has increased surveillance of farm workers, veterinarians and others exposed to infected animals. In several states, authorities are testing people with unexplained severe respiratory illness for avian flu as a precaution. Internationally, WHO has called on countries to update and rehearse their pandemic influenza plans, drawing on the lessons of COVID-19. At the same time, WOAH continues to collect and share data on avian influenza outbreaks in animals, helping countries coordinate trade measures and outbreak responses.

Experts say that clear communication is essential to avoid both complacency and unnecessary panic. For now, the message from WHO and WOAH is consistent: the virus is not currently spreading between people, but the world should use this time to prepare, not to look away. Many scientists also argue that now is the moment to invest in broader solutions like a “universal flu vaccine” that could offer protection against multiple flu strains, including potential pandemic variants.

Global and Local Impact If the Risk Becomes Reality

If a mutated H5 avian influenza virus did gain the ability to spread efficiently between humans, the global and local impacts would be enormous. At a global level, a severe flu pandemic could disrupt international travel and trade, trigger lockdowns or movement restrictions, and cause widespread economic damage. Food systems would be particularly affected, since poultry remains a critical source of protein in many countries. Farmers who are already vulnerable after repeated culls could be pushed into bankruptcy, and governments might need to subsidize food supplies and compensate for massive losses in the agricultural sector.

At a local level, health systems would be under intense pressure. Hospitals would need to rapidly expand intensive care capacity and manage large numbers of patients with severe respiratory distress. This would come on top of existing health burdens such as diabetes, heart disease and other chronic conditions, which GSN has been tracking closely in its health coverage. In lower-income regions, where hospital capacity and access to advanced care are limited, the human cost could be especially high. Public health measures such as mask mandates, school closures and restrictions on gatherings could return, testing community resilience and trust in authorities once again.

On the environmental side, a severe wave of bird flu brings additional consequences. Large die-offs of wild birds can disrupt ecosystems, especially along migratory flyways. Conservation groups warn that rare or endangered bird species could be pushed closer to extinction if outbreaks hit sensitive populations. The One Health approach — which recognizes the links between human, animal and environmental health — therefore becomes essential. Protecting wetlands, regulating intensive farming, and monitoring wildlife health are not just conservation issues; they are also pandemic prevention tools.

A Warning the World Cannot Ignore

The bird flu mutation risk is a warning the world cannot afford to ignore. Scientists at Institut Pasteur and other leading centers stress that H5N1 has not yet become a human pandemic virus, but the ingredients for that transformation — widespread circulation in birds, spillover into mammals, occasional human infections and a lack of population immunity — are already in place. Whether this risk becomes reality will depend in large part on what governments, health agencies and communities do now.

Preparedness does not mean panic. It means strengthening surveillance in animals and humans, investing in vaccine and antiviral capacity, protecting farm workers and veterinarians, and communicating clearly with the public. It also means taking a broader view of health, recognizing that issues like climate change, industrial farming, and chronic diseases all influence how vulnerable societies are to a new pathogen. If the world acts on the bird flu warning with seriousness and foresight, it may be possible to prevent a future outbreak from becoming a catastrophe. The challenge is to learn from COVID-19 — and to treat this emerging risk not as a distant hypothetical, but as a test of our collective readiness.