Several viruses in circulation around the globe require constant year-round surveillance , even if some are seasonal. This monitoring, carried out in large part by the National Reference Centers (CNRs) at the Institut Pasteur, enables decision-makers to anticipate appropriate scientific, medical and health measures if the viruses begin to circulate among the population and in households across the country. At this time of year, the CNR for Respiratory Infection Viruses is on particular alert.

There seems to be no let-up in cases of influenza ahead of the 2025 festive period. According to the latest bulletin published by Santé publique France (SpF) on Wednesday December 3 (in French), cases of influenza are "rising sharply." Greater Paris, Normandy and Nouvelle-Aquitaine are currently at "epidemic" alert level, the highest SpF level. The other French regions are at "pre-epidemic" level, apart from Corsica. Surveillance, analysis and research are conducted on a daily basis to monitor and trace the virus and prevent it from spreading throughout the population.

Another virus under close surveillance is avian influenza. Avian influenza has hit the headlines this year. Since 2022, the world has been grappling with a severe epizootic of avian influenza, affecting birds and sometimes also farmed mammals, primarily caused by the influenza A(H5N1) virus. Some sporadic cases have been observed in humans, but so far these have only been people who have come into close contact with infected animals. The H5N1 virus is circulating in all world regions apart from Australia. One milestone in this ongoing epidemic was the spread of avian influenza to dairy cows, confirmed by WHO in May 2024. The global epidemic that we are currently witnessing is also affecting France. Wild birds have been severely affected, with some mass fatalities. This year, a number of domestic poultry farms in Brittany and south-west France in particular have been contaminated by wild birds.

In this pandemic context, the Institut Pasteur is a key player in monitoring, analysis and modeling, in addition to its ongoing scientific research aimed at improving our ability to tackle respiratory viruses. 

Respiratory viruses, seasonal flu and avian flu – see some of the media contributions by the Institut Pasteur's experts in the field:

• Respiratory viruses

Watch the interview with Marie-Anne Rameix-Welti on France Info TV, December 11, 2025 (starting at 1:09:08) (in French)

Read the article on winter respiratory viruses (coming soon)

• Seasonal flu

Read the article in Santé magazine dated December 11, 2025, in collaboration with Marie-Anne Rameix Welti, head of the CNR Respiratory Infections Virus: ‘Early flu epidemic (map dated December 10, 2025): why is the K variant worrying epidemiologists?’ (in French)

See the video posted on December 5, 2025 on Instagram with Vincent Enouf discussing the topic of influenza (in French)

Watch the interview with Vincent Enouf in the program "C à vous" on December 4: “Influenza epidemic: what we can expect this year” (in French)

Read the interview with Vincent Enouf in Ouest France on December 3: "Even if the flu strain is not in the vaccine, it still protects against severe cases" (in French) 

• Avian flu

Read the article in Santé magazine on December 8 in collaboration with Marie-Anne Rameix Welti, head of the CNR Respiratory Infections Virus: "Avian flu: is it safe to eat poultry at Christmas?" (in French)

Read the article in Le Parisien on December 8,2025: "A pandemic is possible": avian influenza, the virus threatening the planet (in French)

Read the article in Santé magazine on December 5 featuring in collaboration with Marie-Anne Rameix Welti, head of the CNR Respiratory Infections Virus: “Avian flu: should we be concerned? An update on the situation in France and around the world with the Institut Pasteur” (in French)