visualize the increase in cases, hospitalizations and mortality

The flu continues to gain ground in France. In the week from Monday January 6 to Sunday January 12, the incidence rate of influenza viruses rose to 231 new cases per 100,000 inhabitants, according to health monitoring figures published by the Sentinelles network. Very high viral circulation, which exceeded the epidemic threshold (179) quite early in the season, since flu epidemics generally experience the bulk of their activity in January-February.

If the progression of influenza viruses experienced a decline during the Christmas school holidays, this was expected. “For influenza, children are really the driving force of transmission within the population. Often, we continue to see this decline the first week of the school year, but there, it is already starting very strongly again among children and adults.explains to Monde Sibylle Bernard-Stoecklin, epidemiologist in the infectious diseases department of Public Health France (SPF). The fact that activity is picking up so quickly in community medicine worries us, since this may herald an upward resumption of hospital indicators during the week. [du lundi 20 au dimanche 26 janvier]. »

SOS Médecins also notes very high levels of intervention at home for cases of flu: as of January 12, more than one intervention in five concerned influenza syndromes, close to 25% reached at the end of December 2022 (the record for the 2010 period -2025).

The pressure on the hospital, already strong, could increase

The epidemic is already putting great pressure on the hospital system. As of Tuesday, January 14, around a hundred establishments had activated their blank plan, consisting of deprogramming non-urgent operations to free up beds and resources, in order to cope with the influx of patients presenting serious forms of influenza, according to the Ministry of Health.

A figure from the Oscour network, closely followed by SPF, reflects the pressure weighing on hospitals: during the first week of 2025, 5.2% of patients admitted to emergency rooms came for a flu-like illness. The extremely high level of this indicator (which is usually between 1% and 1.5%) is partly explained by a reduced number of doctors during this period, but also by the fact that the “speed bump” role of leave school has not yet been felt in the hospital. Indeed, we always observe a lag of one to two weeks between the “front” of the epidemic (contaminations) and the consequences on the healthcare system.

The ratio of patients admitted for influenza-like illness certainly fell to 4.3% in the second week of January, but this decline could unfortunately only be temporary, due to the rapid resumption of viral circulation in all classes of patients. 'age

The trend is the same for hospitalizations in the broad sense: the share of influenza in admissions reached 5.4% at the beginning of January, the highest level ever recorded since this indicator from the Oscour network exists (October 2017).

Seniors (65 years and over) are particularly affected this season, particularly in intensive care units, where they represent 46% of flu patients, the largest share of this age group since the 2018 season. 2019.

A sharp increase in mortality

If it is difficult to describe an epidemic that is still ongoing (epidemiologists publish the results of the flu season at the beginning of summer), the one currently raging seems to be characterized by marked mortality in recent weeks. Influenza is mentioned among the causes in 7.3% of electronically certified deaths, unheard of since 2017, when SPF has used this metric as a health monitoring tool. We are well beyond the levels recorded previously, which never exceeded 4.5%.

“Our indicators, whether in hospital or in terms of deaths, clearly show the severity of the flu epidemic this year”notes Sibylle Bernard-Stoecklin. This could result in excess mortality higher than the 9,000-10,000 deaths that an epidemic causes on average. every year.

The reasons for possible excess mortality are difficult to assess, especially since we have limited hindsight on the current epidemic. “The situation is truly atypical this year, with the joint circulation of three viruses. But from a virological point of view, we currently have no evidence that would allow us to say that these strains are more virulent than in previous years.specifies M^me Bernard-Stoecklin.

Could the severity of the epidemic be explained by the low vaccination coverage this year? Difficult to say, although it is widely documented that each point of variation in vaccination coverage among the elderly has an impact on deaths. “Data shows that the vaccine prevents 2,000 deaths on average each year, despite the low vaccination coverage and its suboptimal effectiveness”recalls the epidemiologist. The vaccination campaign, still ongoing, is due to end on January 31. But the flu epidemic could have exceeded its peak intensity well before then.