the figures showing the haste of the epidemic this season

While the coronavirus circulates less and the bronchiolitis epidemic is decreasing and remains at a high level, the spread of influenza is accelerating throughout France at the end of 2022. The Minister of Health, François Braun, mentioned on Wednesday 28 December, “a week with all dangers”. “There is an explosion of cases [de grippe]with also serious cases, which means that resuscitation services are globally saturated”, said the former emergency physician. Hospitalizations for influenza-like illness have actually increased by 75%, Public Health France (SPF) said in its latest epidemiological bulletin.

Also read: With a “triple epidemic” of Covid-19, bronchiolitis and influenza, the “week of all dangers” for the French health system

Several indicators show that the flu is early this season. According to data from the Sentinelles network, which brings together more than 1,300 liberal practitioners, the number of consultations for influenza-like illness was estimated at 460 per 100,000 inhabitants in the penultimate week of 2022. This figure is very high for this period. of the year compared with the last ten years, when the peak of the epidemic generally occurred between February and March.

The proportion of flu-like illnesses among SOS doctors’ consultations also provides information on the scale of the epidemic. For eight weeks in a row, these consultations have been increasing and are earlier than in previous years.

The proportion of hospitalizations for influenza at the highest level since 2010

Hospital data also show that the epidemic is gaining momentum. In all age groups, the number of visits to the emergency room for influenza has continued to increase (+ 52% compared to week 50), as has the number of hospitalizations after a visit to the emergency room for influenza (+ 75% in one week) ).

Health authorities note that the proportion of hospitalizations for influenza or influenza-like illness in the week of December 19 reached 41.2 per 1,000 admissions for all causes combined, i.e. “highest value observed for this indicator in the period 2010-2023” same week of the year.

Also read: Article reserved for our subscribers Covid-19, bronchiolitis and influenza: the triple epidemic of respiratory viruses threatens France this winter

Since October 3, at least 193 serious cases of influenza have been hospitalized in intensive care, of which 142 since December 5. Among them we find mainly seniors (80 were 65 years or over), but also younger: 16 were between 0 and 4 years, 16 between 5 and 14 years and 79 between 15 and 64 years, according to the weekly bulletin of the SPF, which specifies , that these data are based on around forty intensive care units and are not exhaustive.

An increasing positivity

Like the SPF shade, certain indicators taken into account in influenza surveillance are based on patients’ symptoms, which tends to influence the data during the Covid-19 pandemic. “It is therefore likely that some of the cases of influenza-like illness reported by our influenza surveillance are due to Covid-19 and not influenza.”says the organization.

“This is the ambiguity of the term ‘influenza syndrome’, which can relate to several diseasescomments Vincent Enouf, deputy head of the National Reference Center for Respiratory Infection Viruses at the Institut Pasteur. We must therefore look at the side of the tests, whose positivity for influenza has increased in recent weeks. » In urban medicine, the Sentinels network reported a 65.3% positivity rate in week 51, up from 56% the previous week. In hospitals, the positivity rate was 20.1% compared to 13.9% two weeks earlier.

“In the past, epidemics where H3N2 was the majority were stronger, more virulent and caused more deaths”

“We are facing the earliest influenza epidemic in at least a decade.notes Sibylle Bernard-Stoecklin, epidemiologist in the Department of Infectious Diseases in the SPF. It came two weeks earlier than in 2017-2018, which was already one of the earliest. » This specificity has been observed elsewhere in Europe, in North America, but also in Australia and New Zealand this summer, while last season’s epidemic, on the contrary, was very late – it started in March. However, the epidemiologist clarifies this “the time of year when an influenza epidemic occurs is not necessarily correlated with its severity”.

Difficult to predict the peak or duration ofepidemic

Vincent Enouf shares this observation: “What will tell us if it’s a big epidemic is the majority virus. » In mainland France, subtype A (H3N2) remains the most prevalent, although an increase in the detection of type B viruses (Victoria) has been observed for several weeks. “A (H3N2) is a virus that evolves faster than others, adapts better and has a greater ability to escape the vaccineexplains the researcher from the Institut Pasteur. Looking at the past, the epidemics where A (H3N2) predominated were stronger, more virulent and caused more deaths, especially among people at risk, such as [coronavirus] SARS-CoV-2. »

“However, just because the A (H3N2) virus is in the majority at the start of the epidemic does not mean that it will remain so throughout the season.specifies Sibylle Bernard-Stoecklin. This is especially the reason why it is still very difficult to predict the peak of the epidemic or how long it will last: there may be a backlash carried by another virus. »

Influenza causes between 10,000 and 15,000 deaths each year, according to the Institut Pasteur, health authorities point out“emergency” to be vaccinated for people at risk and remember the importance of barrier movements, especially during the celebrations of the end of the year. In 2021-2022, only 56.8% of people over 65 were vaccinated against influenza. For this season, the figures are not yet known.

also read Seasonal flu vaccine: who is encouraged to get it and why

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