2024-02-09 15:52:24
Right now, it’s hard to slip through the cracks. Since mid-January, the entirety of mainland France has been in an epidemic phase for influenza. At work, in the family or among friends, everyone notices that the virus circulates happily, passing from an infected person to their neighbor at great speed. In this context, a question arises: the strain of the flu which imposed this winter in France is it more contagious than in previous years? No, replies Pierre-Yves Boëlle, professor of epidemiology…
Right now, it’s hard to slip through the cracks. Since mid-January, the entirety of mainland France has been in an epidemic phase for influenza. At work, in the family or among friends, everyone notices that the virus circulates happily, passing from an infected person to their neighbor at great speed. In this context, a question arises: the strain of the flu which imposed this winter in France is it more contagious than in previous years? No, replies Pierre-Yves Boëlle, professor of epidemiology at Sorbonne University and at the National Institute of Health and Medical Research (Inserm).
“The strain of the virus currently circulating is A (H1N1), he explains. The flu virus is still evolving a little but, for the moment, we have no reason to think that it is more virulent than in other years. » According to the researcher, “today, we have returned to traditional influenza epidemiology”.
“Systems are realigning”
If the 2023-2024 flu epidemic is therefore approaching the standards before the Covid-19 crisis, Sars-CoV-2 has nevertheless left its traces, admits Pierre-Yves Boëlle. In 2020-2021, in the middle of a pandemic, “we didn’t have the flu,” he recalls. In adults, this absence probably did not cause a drop in immunity, protection after an infection being “of the order of five to seven years”, recalls the doctor. But, he adds, the situation is different among children.
“They were less exposed during this period and at home, there are undoubtedly more who remained susceptible to the flu. » An explanation, perhaps, for the massive spread of the virus: if children are more easily contaminated, the risk is great that the adults around them will also end up being infected, especially since the reflex of barrier gestures has been lost considerably in recent years…
“Covid has significantly disrupted the epidemiology of respiratory viruses”
Pierre-Yves Boëlle also observed a “change in the types of manifestations” after cases of flu, notably fatigue and a cough that was more persistent than usual. “It’s one of the things that we noted empirically,” he reports. We wonder: is this a change in symptoms linked to the flu or are other intercurrent viruses there? Is this a consequence of the lack of immunity we had during Covid? These are questions to which we do not have the answers today. »
The researcher and his colleagues are also trying to understand why, for two years, “Covid has been decreasing when influenza is increasing”, when “there is no direct competition between these two viruses”. Here again, the mystery remains: “It is quite reasonable to say that Covid has quite disrupted the epidemiology of respiratory viruses,” he summarizes. We are still in a phase where all these systems are adjusting in relation to each other, without us clearly understanding what the determining factors are. »
“We are seeing a significant increase in calls to center 15. Emergencies are also in high demand and we are seeing many cases in intensive care”
Hospitalizations on the rise
One thing is certain, this return to a classic flu epidemic is not good news. Every year, “2 to 6 million” French people fall ill, and 10,000 die, of whom “more than 90%” are seniors aged 65 and over, according to official figures. Where are we in France at the moment? In the tough, certainly, and the peak has not yet been reached…
Between January 29 and February 4, according to Public Health France (SpF), the number of flu cases treated in community medicine remained stable, at a high level (18%), while an increase was noted in hospitals. After a visit to the emergency room, the virus now represents 3.1% of hospitalizations, a “high level of intensity for all ages”, SpF alert. “We are seeing a significant increase in calls to center 15,” confirms Professor Charles Cazanave, infectious disease specialist at Bordeaux University Hospital. Emergencies are also in high demand and we encounter many cases in intensive care.”
The good news this winter concerns the vaccine: its “effectiveness” is “between 60 and 65%” against “the A (H1N1) strain, the majority this year”, says Bruno Lina, director of the National Virus Reference Center respiratory infections, quoted by Le Point. It remains to convince the most vulnerable to take the plunge, while the vaccination campaign has been extended until February 29. At the end of November, only 42.8% of those aged 65 and over had been vaccinated, a figure down compared to the previous year. “As long as we have not reached the peak, it is always useful to be vaccinated,” recalls Pierre-Yves Boëlle.
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