Even if, since 2020, the Covid-19 virus is the one that has aroused the most interest (and concern), seasonal flu virus has not however disappeared. In mainland France, this contagious viral infectious disease generally occurs between the months of December and April. And as the new vaccination campaign starts this Tuesday, October 18, Public Health France has taken stock of the 2021-2022 epidemic season.
2021-2022 epidemic: it was exceptionally late
During the previous influenza epidemic (that of the 2021-2022 season), the active circulation of influenza viruses began in mid-December 2021 in mainland France and spread fairly slowly to all regions for about two months. . Then an epidemic resurgence was detected from March and the epidemic reached its peak at the national level at the beginning of April, to end at the end of April, i.e. 9 weeks of epidemic. “No other influenza epidemic had reached its peak so late during the period 2009-2022” emphasizes Public Health France.
During this period, co-circulation of the A(H3N2) and A(H1N1) viruses was recorded. And among the 143,685 deaths declared in metropolitan France by electronic death certificate, 594 (i.e. 0.4%) were declared with a mention of influenza as a morbid condition having directly caused or contributed to the death.
>> Read also:why is the flu epidemic likely to be more severe this winter?
Epidemic 2021-2022: children under 15 were the most affected
During last year’s epidemic, the number of consultations for flu-like illness was estimated at 961,000 based on data from the Sentinelles network. Consultations for flu syndrome in city medicine concerned very mostly young people under 15. With a cumulative incidence rate of 3,624 cases per 100,000 inhabitants in children under 5 years old and 2,926 cases per 100,000 inhabitants in children aged 5 to 14 years.
This rate is much lower among 14-64 year olds (1,312 cases per 100,000 inhabitants) and among those over 65 (524 cases per 100,000 inhabitants).
Epidemic 2021-2022: more children hospitalized too
: during the outbreak, the Oscour® network reported 56,742 visits to the emergency room for flu, i.e. 18/1000 emergency room visits, which is comparable to the average of 19/1000 emergency room visits during the epidemics from 2015 to 2019 (the epidemics of 2020 and 2021 were excluded from the statistics due to the predominance of Covid- 19). 35% of these visits to the emergency room concerned children under 5 years old, 26% those aged 5-14 years, 30% those aged 15-64 years and 9% those aged 65 and over.
>> Hospitalizations for flu : 12% (6712 passages) resulted in hospitalization, a value comparable to the average of 13% observed during previous epidemics. The share of children under 15 among hospitalizations was 30% (compared to 18% in 2018-2019) and the share of people aged 65 and over was 45% (compared to 62% in 2018-2019).
2021-2022 epidemic: 479 serious cases including 54 deaths
479 serious cases of influenza have been reported among the 211 intensive care units invited to participate in this surveillance, including 333 cases during the epidemic period. “This number is significantly lower than that observed during previous epidemics and makes this season the second lowest year in terms of the number of cases admitted to the intensive care unit” underlines Public Health France.
The average age of people in intensive care was 48, a lower age than in previous epidemics. But a high number of cases concerned children under 15 years old (with 45% of cases in children under 2 years old, 18% in 2-4 year olds, and 37% in 5-14 year olds). The majority of cases (72%) had at least one serious influenza risk factor (age, chronic illness). The most frequent comorbidities were pulmonary pathologies (61%), cardiac pathologies (36%) or diabetes (25%).
>> 54 deaths have been reported in total, 80% of whom had at least one risk factor. Among these deaths, 3 occurred in children under 2 years of age, none of whom had a risk factor, 22 in people aged 15 to 64 and 29 in people aged 65 or over.
How to know when the epidemic is declared?
Since the 2016-2017 season, the determination of the pre- and post-epidemic periods, as well as the influenza epidemic period at the national level and in the regions, is carried out from the data transmitted by three sources of consultations for syndrome flu:
- the Sentinelles network, which brings together 1,200 general practitioners and 120 pediatricians
- SOS Médecins, which provides round-the-clock care 7 days a week, 24 hours a day)
- the Oscour® network, which brings together 700 hospital emergency departments.
In communities for the elderly, surveillance focuses on episodes of grouped cases of acute respiratory infections (excluding covid) reported by establishments caring for the elderly to regional health agencies (ARS).
Depending on the number of alerts generated, each region and metropolitan area are considered to be in the pre- or post-epidemic phase or in the epidemic phase.
Source :Weekly epidemiological bulletinPublic Health France, October 18, 2022
