The epidemiology of avian and swine influenza viruses currently requires heightened vigilance. Since 2021, the H5N1 avian virus has been circulating extensively among birds worldwide, including in France, and has caused massive outbreaks in poultry farms and among wild birds, with a major impact on the poultry industry. An unprecedented variety of wild mammals have been affected, including domestic animals. Human cases are regularly detected internationally; this is referred to as avian influenza. Although most cases are mild, severe forms have been observed in several patients. In 2024, 80 human cases were detected, mainly in the United States and Asia, but no cases were reported in France. One case was detected in late January 2025 in England.

Swine influenza viruses also circulate throughout the year and are capable of infecting humans. Although human cases are generally mild, the regular exchange of influenza viruses between pigs and humans increases the risk of the emergence of a new virus with pandemic potential, as occurred in 2009.

3 Questions for Sibylle Bernard-Stoecklin, an epidemiologist at Santé publique France

Should we be concerned about the international situation?

To date, no cases of human influenza linked to an avian influenza virus have been detected in France. The World Health Organization (WHO) and the ECDC (European Centre for Disease Prevention and Control) consider that the risk posed by avian influenza viruses with zoonotic potential currently circulating is low for the general population, and low to moderate for people directly exposed to these viruses. However, due to the genetic evolution of influenza viruses, there is a risk of the emergence of a virus capable of efficient human-to-human transmission, which could lead to an epidemic or even a pandemic. The widespread circulation of A(H5N1) viruses globally, with a particularly dynamic situation in the United States since the fall of 2024, increases the risk of a virus emerging that is better adapted to humans.

Consequently, the current situation is being closely monitored by international experts and calls for strengthened prevention and surveillance measures due to the risks of a new virus emerging that is better adapted to humans.

What measures have been put in place to monitor the current situation?

Santé publique France is fully engaged, in collaboration with its national and international partners (ECDC, WHO), in preventing the transmission of zoonotic viruses (avian and swine influenza) to humans, as well as in surveillance to conduct virological and epidemiological investigations should cases arise within the country. The agency also provides scientific monitoring and expertise to public authorities on the epidemiological situation of influenza viruses with zoonotic potential and the risk analysis these viruses pose to human health. This work is carried out in collaboration with the National Reference Center for Respiratory Infectious Viruses, healthcare professionals, animal health stakeholders, and the Mutualité sociale agricole (MSA), as part of a “One Health” approach.

Several measures have been implemented in recent years:

1. Information and Prevention: Since 2023, a brochure has informed at-risk individuals (livestock farmers, veterinarians, hunters, animal caretakers, etc.) about the risks of zoonotic influenza viruses, preventive measures, and the steps to take in the event of exposure. It also raises awareness among healthcare professionals and informs them of the procedures for managing patients suspected of having influenza of animal origin. It reiterates the recommendation for seasonal flu vaccination, in effect since 2022, for individuals exposed to the viruses.

2. Update of the so-called “passive” surveillance protocol: In January 2025, the protocol for monitoring cases of zoonotic influenza was updated to account for recent changes in the epidemiology of animal influenza viruses that pose a risk to human health.

3. Implementation of an enhanced “active” surveillance protocol: since late 2023, an active surveillance protocol for avian influenza (SAGA) has been launched in the four regions most affected by highly pathogenic avian influenza (Brittany, Nouvelle-Aquitaine, Occitanie, and Pays de la Loire). This system, tested during the 2023–2024 season, was renewed this winter in the same regions. Work is underway with all our partners to optimize it and, ultimately, extend it to the entire country.

What should you do if you’ve been exposed to a risk? How can you protect yourself?

It is strongly advised against touching or picking up sick or dead wild birds or mammals. If exposed to infected animals or an environment contaminated with avian influenza virus, it is essential to protect yourself by wearing appropriate personal protective equipment and following preventive measures:

• wear protective clothing,

• wear a respiratory protection mask (preferably FFP2), goggles or a face shield, and waterproof gloves,

• wash your hands after each contact with animals or contaminated surfaces, even if you are wearing protective gloves.

In the event of potential exposure, it is recommended to monitor your health for 10 days. If symptoms appear (fatigue, fever, body aches, cough, breathing difficulties, etc.), you should:

• limit contact with others,

• wear a surgical mask when around others,

• follow preventive measures,

• immediately consult a doctor, who will order a test to identify influenza A virus and rule out infection with a human virus.