Santé Publique France published on November 16 the results of the monitoring of seasonal flu for the week 45 (November 7 to 13).
1. Situation en metropolis
The Brittany has entered the pre-epidemic phase in S44 (first week of November), the influenza activity indicators remained at their basic level in the other regions.
However, some indicators are increasing :
- In general practice, an increase in activity for flu-like illness was observed in all metropolitan areas compared to the previous week. The increase concerned all age groups but was more marked in the under 15s, particularly the under 5s.
- In the hospital, influenza activity was generally stable, except in Hauts-de-France, Normandy and Provence-Alpes-Côte d’Azur, where it progressed in mid-November. In the emergency services, we observe an increase in flu-like illnesses and corresponding hospitalizations in people under 15 at metropolitan level (respectively +10% and +28%), unlike in other age groups. These syndromic data should be interpreted with caution in the current context of high circulation of various respiratory viruses, particularly in young children.
Virological monitoring: a majority circulation of the A(H3N2) virus has been noted since the beginning of October 2022:
- In general practice, out of 684 samples taken, 48 were positive for the influenza virus with 41 A(H3N2) subtype viruses, 5 A(H1N1)pdm09 subtype viruses and two not yet subtyped. Two cases of A(H3N2)/SARS-CoV-2 co-infection have been identified.
- In hospitals: out of 31,347 virological results sent to the National Reference Center (CNR) for respiratory infection viruses369 samples tested positive for an influenza virus, including 53 from November 7 to 13, 2022, with 308 type A viruses [65 A(H3N2), 20 A(H1N1)pdm09, 223 non encore sous-typés] and 61 type B viruses.
2. Overseas
Three regions were always in epidemic mi-november 2022 :
- The Meeting since the end of September 2022, with a majority circulation of the A(H1N1)pdm09 virus;
- the Martinique since mid-October 2022, with a majority of A(H3N2) viruses;
- et Mayotte since the beginning of November 2022, with circulation mainly of the A(H1N1)pdm09 virus.
If an epidemic circulation of influenza viruses is frequently observed in October-November in Reunion, the occurrence of an influenza epidemic at this time of year is however atypical in the West Indies and Mayotte.
3. Other Northern Hemisphere countries
Currently, influenza cases are increasing in Europe and elsewhere in the Northern Hemisphere, particularly in North America (USA and Canada), where influenza activity is above the levels usually seen at this time of year.
4. Southern Hemisphere
The importance of the influenza epidemics observed in certain countries of the southern hemisphere could announce an increase in the number of cases during the winter season of the northern hemisphere. Australia, which experiences winter from June to August, experienced a strong and particularly early flu epidemic this year, mainly caused by a subtype of H3N2 covered by the vaccine used.
5. Conclusions
Ending social distancing, mask-wearing, and other covid-19 pandemic mitigation measures could lead to more severe influenza infections in the Northern Hemisphere. In this context and taking into account the results of epidemiological surveillance, Santé Publique France concludes that an influenza epidemic occurring early in mainland France cannot be ruled out this year.
It is therefore strongly recommended that people at risk and healthcare professionals get vaccinated against seasonal flu without delay.
In addition, the systematic adoption of barrier gestures by all remains an effective means of protecting against influenza and its complications, and of limiting the risk of transmitting the virus to those around them.
Source: Public Health France.