H5N1 should now be treated as a permanent systemic risk, not a succession of outbreaks

Highly pathogenic avian influenza has moved beyond the model of episodic poultry outbreaks and should now be managed as a persistent, multi-host systemic risk. A study argue that the combination of sustained circulation in wild birds, repeated mammalian spillover, environmental contamination and recurrent farm outbreaks makes a return to a stable disease-free baseline increasingly unrealistic.

The shift became particularly visible during the 2025 autumn migration season in Europe. Between September and November, laboratory-confirmed HPAI detections in wild birds were reported in 29 countries, across the major East Atlantic, Black Sea–Mediterranean and Central Asian flyways. Including captive and domestic birds, 2,896 outbreaks were notified, around six times more than during the same period in 2024 and 12 times more than in 2023.

A broader host range changes the risk

The virus is no longer circulating mainly between wild birds and poultry. The paper notes infection in more than 50 mammalian species, including marine mammals, carnivores and livestock. The establishment of H5N1 in US dairy cattle marked a major epidemiological change: by February 2026, more than 1,000 cattle outbreaks across 19 states had been reported, with evidence of farm-to-farm spread and secondary human infections among exposed workers.

This expansion creates more opportunities for viral adaptation and reassortment. The authors stress that the present low risk to the general human population does not mean the situation is biologically stable. Influenza risk can change abruptly when specific mutations, receptor adaptations or reassortment events cross critical thresholds.

Classical stamping-out strategies are reaching their limits

Traditional HPAI control has relied heavily on culling infected flocks, movement restrictions and restoration of disease-free status. But when virus is repeatedly reintroduced from wildlife and continues circulating within poultry production systems, these measures can reduce local impact without eliminating the underlying source of risk.

The economic consequences are already substantial. Around 4.7 million poultry died or were culled in November 2025, mostly in Europe. In the United States, more than 173 million birds have died or been culled since 2022, while outbreak-control costs exceeded $1.4 billion by late 2024.

Vaccination becomes a structural component of control

The authors therefore place vaccination at the centre of a more resilient strategy. They do not present it as a replacement for biosecurity or surveillance, but as part of an integrated package including DIVA approaches, targeted monitoring and rapid detection.

France’s preventive duck vaccination programme, introduced in 2023 and maintained through 2025, is cited as an example of vaccination becoming a permanent part of national HPAI policy. Italy, the Netherlands, China, Vietnam, Egypt and South Africa have also adopted or prepared vaccination approaches in selected poultry sectors.

The central argument is that H5N1 control should now move from emergency eradication toward long-term resilience: surveillance adapted to endemic circulation, vaccination integrated with trade policy, stronger wildlife–livestock–human coordination and acceptance that persistent infection pressure will remain part of the epidemiological landscape.