Assessment on the health risks associated with Highly Pathogenic Avian Influenza (HPAI)
Creators: name: Comité de veille et anticipation des risques sanitaires (COVARS)
Publisher: name: Zenodo
Year: 2023
Subjects: HPAI
avian flu
avian influenza
prevention strategies
one-health
surveillance systems
Epidemiological Analysis
Interagency Collaboration
Research Prioritization
Occupational Safety

description: Avian influenza, due to Influenza A viruses, is a severe and highly contagious viral infection affecting domestic and wild birds and can be transmitted to humans.  The highly pathogenic avian influenza (HPAI) outbreak of 2021-2022 has caused an unprecedented crisis in France and worldwide, leading to the preventive slaughter of more than 21 million poultry in France, with some mammal cases raising a major risk to human health. While the French situation seemed quieter in March 2023, when the Ministry of Agriculture lowered the risk level from "high" to "moderate", new outbreaks have occurred since then in farms in the south-west of France, bringing back HPAI to the forefront of health risks. The threat of an endemization indeed raises health issues for birds, mammals and humans who can contract avian influenza through close contact with a sick animal, as well as socio-economic issues: in France in 2022, economic losses related to HPAI amounted  to more than one billion euros. Following the death of a child from an H5N1 Flu in Cambodia, the WHO has estimated the situation as "worrying" in February 2023, calling for a vigilance increase in all countries.

Several factors make HPAI a particularly significant risk (Part I-C). First, HPAI cannot be eradicated because of the immensity and diversity of its reservoir. Second, the rapid HPAI transmission between birds and its severity causes high mortality in wild birds and increases the risk of IAHP becoming endemic. It also increases the risk of transmission to and between mammals, particularly in the case of the A (H5N1) virus. Climate change and the biodiversity crisis are altering the trajectories of wild birds and their resistance to viruses, which could also be a source of new HPAI outbreaks. The loss of seasonality in avian infection, the increase in the number of cases in farms, the diversification of the affected wild species and the increase in mammal cases reinforce the public health risk for humans, even though there have not yet been any confirmed cases of human-to-human transmission of avian influenza. 

In France, a passive surveillance of wild birds is orchestrated by the SAGIR network (Part II-A-1). The farm surveillance allows the detection of cases leading to biosecurity and management counter-measures in line with the recommendations of the ANSES. However, these measures are unevenly followed by the poultry farmers and can raise socio-economic challenges that need to be taken into account by the public authorities (Part II-A-2). Human surveillance is currently focused solely on symptomatic cases, but the SAGA protocol, currently in development by health and veterinary agencies, will set up active monitoring among professionals exposed to the risk of avian influenza (poultry farmers, workers and veterinarians).

A strategy for vaccination of poultry against HPAI, has been authorised and recommended in 2022 at the European level (Part II-A-3), and will shortly be finalised in France thus enabling preventive vaccination in duck farms to begin in autumn 2023. Vaccination of poultry farmers and poultry industry professionals against seasonal influenza is also now recommended in order to limit the risk of recombination between avian and human viruses, which could create a risk of avian influenza. Pandemic and pre-pandemic vaccines are currently being developed. While conventional antiviral treatments are available in France, new anti-virals already authorised in some countries offer numerous advantages for human cases of avian influenza (Part II-A-4) and should play a key role in an avian influenza pandemic preparednesse and management, pending the deployment of an adapted human vaccination strategy. Finally, research programmes on avian influenza (Part II-B) are underway.

This assessment incorporates all existing anticipation and surveillance mechanisms and puts forward proposals to strengthen these pandemic risk prevention systems related to Highly Pathogenic Avian Influenza (HPAI), while supporting upstream research needs, with a strong One Health component.

Its preparation was informed by exchanges between COVARS and the main stakeholders in the field. The COVARS recommendations (Part 1) are based on the situational and epidemiological overview (Part 2), as well as the analysis of prevention and management measures (Part 3), and take into account the recommendations from ANSES, Santé publique France (SpF), and the Haute Autorité de Santé (HAS) regarding the prevention and management of avian influenza, including the protection of professionals in contact with animals.