The bird flu, scientifically known as avian influenza, has sparked growing concern among public health experts worldwide. In recent months, the highly pathogenic H5N1 strain has been detected in new hosts, such as domestic mammals, including dogs and cats, while continuing to circulate among wild and farmed birds. Although human-to-human transmission has not yet been confirmed, the World Health Organization (WHO) has recorded approximately 900 cases of human infection across 23 countries over the past two decades, with a mortality rate reaching an alarming 50% in some instances. This silent progression of the virus, described by some as a “pandemic in the making,” reignites debates about global preparedness for a potential large-scale outbreak, especially in light of lessons learned from the Covid-19 crisis.
Recent cases in the United States reveal that the virus is no longer confined to birds. Since early 2024, dairy farms have reported infections in cows, an unusual development that broadens the possibilities for mutation and adaptation of H5N1. French health authorities, meanwhile, celebrate a season without significant outbreaks in their poultry farms but maintain stocks of vaccines and antivirals as a precaution. The fear is that increased interactions between species, driven by factors such as deforestation and animal trade, could create the perfect conditions for the virus to jump to humans.
Amid this scenario, scientists warn that the next pandemic may be closer than we think. The WHO is already working with the concept of “Disease X,” a hypothetical threat that could emerge from pathogens like bird flu. Countries such as France and the United Kingdom have stepped up surveillance, while the United States struggles to contain the spread within its agricultural sector. Though the risk to the general population remains low for now, it demands coordinated action and robust preparation.
Virus escalation raises expert concerns
H5N1 spreads across species and triggers red alert
The H5N1 virus, first identified in birds in the 1990s, has evolved from a regional threat to a global issue. In the United States, the situation worsened in recent months, with infections reported in dairy herds since February 2024. Farms in East Yorkshire, England, also confirmed cases in commercial poultry earlier this year, prompting the establishment of sanitary control zones. Experts note that the virus’s ability to infect mammals, such as cows, pigs, and even pets, heightens the likelihood of mutations that could enable human transmission. Meg Schaeffer, an epidemiologist at the American SAS Institute, emphasizes that the more species the virus reaches, the greater the chance it adapts to the human body.
In Europe, France adopts a cautious stance. Despite no major outbreaks this season, health authorities have stockpiled vaccines and antiviral drugs, mindful of past mistakes during the Covid-19 pandemic. The WHO stresses that while there is no evidence of sustained human-to-human transmission, the 900 human cases recorded since 2003 demonstrate that the virus can cross the species barrier under specific conditions, such as close contact with infected animals. The high lethality of H5N1, far exceeding that of SARS-CoV-2, makes each new case a cause for concern.
Global preparedness questioned post-Covid-19
The Covid-19 pandemic left deep scars on public health systems and exposed weaknesses that remain unaddressed. In France, former Prime Minister Jean Castex regrets the lack of a comprehensive “lessons learned” review of the crisis, while epidemiologist William Dab criticizes what he calls “forgetfulness bordering on denial.” Five years after the Covid outbreak began, many countries, including powerhouses like the United States and European Union members, seem unprepared for another health emergency. The creation of HERA (European Health Emergency Preparedness and Response Authority) in 2021 is a step forward, but its ability to coordinate continent-wide responses is still under scrutiny.
Path to a possible pandemic
Factors amplifying the H5N1 risk
Several elements converge to turn bird flu into an imminent threat. Increased human-wildlife contact, driven by agricultural expansion and urbanization, is identified as a key trigger. In Asia, live animal markets remain potential hotspots for zoonotic diseases, while in North America, industrialized farming accelerates the virus’s spread. Recent studies show that H5N1 is already circulating in natural reservoirs, such as migratory birds, which cross continents and disseminate the pathogen without geographical barriers. This situation is worsened by global warming, which alters migration patterns and expands interaction points between species.
The lack of human immunity to H5N1 is another critical factor. Unlike seasonal flu, against which populations build some resistance over time, the avian virus is uncharted territory for the immune system. Maria Van Kerkhove, head of the WHO’s pandemic prevention department, stresses the need to “double down on surveillance” to prevent an uncontrolled outbreak. In the United States, where the virus already affects milk and meat production, experts fear that food contamination could become an indirect exposure route, though this has not been confirmed.
Preventive measures underway
Countries are adopting varied strategies to curb the H5N1 advance. Here are some ongoing efforts:
- Enhanced surveillance: The United Kingdom and France have intensified monitoring of wild and domestic birds, with regular testing in farms.
- Strategic stockpiles: France maintains reserves of vaccines and antivirals, while the U.S. works on adapting existing immunizations.
- Sanitary control: Exclusion zones have been set up in affected areas like East Yorkshire to limit spread between farms.
- Scientific research: Global teams are studying viral mutations to anticipate human transmission scenarios.
These initiatives, while promising, face challenges such as lack of international coordination and the high costs of large-scale implementation.
What the future holds for bird flu
Timeline of the threat: Recent H5N1 milestones
The virus’s progression can be tracked through key events illustrating its escalation:
- 2003: First human cases recorded, with high lethality in Asian countries.
- 2014-2015: Massive outbreak in U.S. poultry, leading to millions of birds culled.
- February 2024: H5N1 confirmed in dairy cattle in East Yorkshire, England, and the U.S.
- March 2024: Reports of infections in dogs and cats widen the host spectrum.
This timeline reflects the virus’s growing adaptability, now circulating in previously unlikely environments. Detection in domestic mammals, such as pets, suggests H5N1 is exploring new transmission pathways, keeping scientists on high alert.
Potential impact on humans and economy
Should H5N1 evolve into a human-transmissible form, the consequences could be catastrophic. The 50% mortality rate seen in current cases far exceeds that of Covid-19, which claimed about 170,000 lives in France over five years. A pandemic outbreak could overwhelm already strained health systems, particularly in nations with shortages of medical personnel, as noted by French authorities. Furthermore, the global economy would face significant disruptions, with impacts on food production, such as meat and dairy, sectors already hit in the U.S. by the virus’s spread among herds.
Preparation, in this context, becomes a race against time. European countries like France invest in health infrastructure, while the United States focuses on immediate containment on farms. The WHO maintains that “we’re not there yet” but insists that global surveillance must be intensified to prevent bird flu from becoming the next major health crisis of the 21st century.