Par
Maxim T'sjoen
Published on
Jan 23, 2025 at 7:44 p.m.
Around a hundred hospitals have initiated white plans in recent weeks. The fault, among other things, is the flu which has been actively circulating in France since the start of winter.
Vaccination is extended until February 28, 2025, announced the Directorate General of Health this Wednesday, January 22.
But how can we explain that the virus circulates like this? Among the answers, the co-circulation of three viruses.
What the numbers say
In France, the flu epidemic is still at “a high level of intensity”, in all age groups, and those aged 65 and over represent 67% of hospitalizations after a trip to the emergency room for flu/flu-like illness. .
In its bulletin of January 22, 2025, Public Health France also noted a “still significant impact” on deaths and “still high” hospital activity for the third week of the year. SPF judges that the flu epidemic is of “marked severity”.
Three viruses, three targets
“Unusual”, the co-circulation of three influenza viruses – two of type A, A (HN1) and A (H3N2), and one of type B/Victoria –, described to have a different impact depending on age groups, could explain this season that all age groups are strongly affected.
This is what the epidemiologist, Sibylle Bernard-Stoecklin, explained for a previous article.
All influenza viruses can infect a person regardless of age and are capable of causing severe illness. But at the population level, the impact of each virus is different depending on age groups.
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HN1 is likely to affect young adults in particular, H3N2 is portrayed as severe in the elderly, and B-Victoria is known to mainly affect children.
What symptoms?
On the other hand, in terms of symptoms, no difference. “The symptoms of influenza infection are not specific, whatever the circulating strains,” confirms actu.fr Antoine Flahault, epidemiologist and director of the Institute of Global Health at the University of Geneva, also author of the book Warn me!.
In terms of symptoms, the epidemiologist reminds us that in around 50% of cases, “contaminated patients can be asymptomatic or paucisymptomatic (that is to say with few symptoms)”.
For the rest, the flu syndrome is “made up of fever, muscle pain, headache, and upper respiratory signs and sometimes also associated digestive signs”.
In a small number of cases, they can develop severe complications that lead to hospitalization or even death, especially when they are very old or immunocompromised.
Small differences between viruses
Antoine Flahault observes a “only difference in clinical expression”: “The H1N1 subtype causes complications less often in the elderly than H3N2. Likewise, type B viruses less often cause fatal complications than type A viruses.
To deal with this active circulation, health authorities are calling for “collective mobilization”. According to them, vaccination and respect for barrier gestures.
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