Swine flu

Influenza viruses that emerge and circulate in pigs all have zoonotic potential, meaning they can infect humans, and sporadic cases are regularly detected. No recent cases of human-to-human transmission of these viruses have been documented.

Updated on 29 October 2025

Our missions

Epidemiological surveillance, validation of case classification in cases of suspected human infection with a swine influenza virus in France, confirmation of cases in collaboration with the National Reference Center for Respiratory Infections, and participation in investigations of confirmed cases, in collaboration with the Regional Health Agency (ARS).
Providing information to public authorities on the epidemiological situation regarding influenza viruses with zoonotic potential

What We Do

An influenza pandemic occurs when a new influenza virus emerges that is well-adapted to humans and capable of being efficiently transmitted from person to person. In previous influenza pandemics, the viruses responsible resulted from genetic exchange between influenza viruses of animal and human origin.

The public health implications of swine flu are therefore significant, and although the risk of a new influenza virus emerging in France is very low, specific surveillance has been in place in France since 2021 to identify potential cases of swine flu—whether imported or locally acquired—as quickly as possible, ensure their prompt medical care and diagnosis, and prevent or, failing that, limit any person-to-person transmission of the virus.

Epidemiological surveillance of swine flu

Santé publique France is responsible for epidemiological surveillance, for validating the classification of suspected swine flu cases as possible cases (requiring a diagnostic sample) reported in France, and for participating in investigations surrounding confirmed cases. In this context, Santé publique France works in coordination with national and international health authorities and relies on the regional network formed by Santé publique France’s regional units, which interact directly with the Regional Health Agencies (ARS).

The objectives of surveillance and investigation of human cases of swine flu are:

to identify early any cases occurring within the country or imported from abroad;
to implement appropriate medical care (particularly with antivirals) and management measures for confirmed cases;
to reduce the risk of the emergence and spread of a virus with pandemic potential by isolating confirmed cases and investigating contacts and co-exposed individuals;
to describe and characterize human cases of infection with avian or swine influenza viruses and their exposures, particularly to inform health authorities as part of international influenza virus surveillance.

Case Identification and Follow-up

Any suspected case of swine flu is reported by the treating clinician to the ARS and forwarded as soon as possible to Santé publique France for validation of the classification as a possible case, in order to conduct virus testing.

If classified as a possible case, the ARS, in coordination with Santé publique France, ensures that a respiratory specimen is sent without delay to the National Reference Center for Respiratory Infection Viruses, completes the questionnaire for possible cases, and monitors possible cases (and, where applicable, confirmed cases) until recovery, death, or exclusion.

Identification and follow-up of co-exposed individuals or close contacts of confirmed cases

The ARS, in collaboration with Santé publique France, identifies and monitors individuals who have shared the same exposure as the confirmed case as well as their close contacts, in order to prevent any risk of human-to-human transmission of the virus.

Information sharing

Public Health France ensures the transmission of information collected during reporting to the relevant national and international health authorities, in collaboration with the ARS.

For healthcare professionals

Public Health France has established a protocol to follow in the event of suspected avian or swine influenza, taking into account the recommendations issued by the High Council for Public Health in its opinion of December 10, 2021. It is available in the document "Surveillance and Investigation of Human Influenza Cases Caused by an Avian or Swine Influenza Virus."

RT-PCR testing for influenza, followed by subtyping of any sample testing positive for influenza A, is required for any person presenting with clinical signs of acute respiratory infection (ARI) or signs of central nervous system involvement (encephalitis or meningoencephalitis) and reporting risk exposure to poultry, waterfowl, or pigs, regardless of the animals’ health status, or to sick or dead wild birds or mammals.