France Faces Potential Second Wave as flu Cases Rebound, Driven by A(H3N2) Variant
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As France continues to grapple with a widespread influenza epidemic, health officials are closely monitoring a concerning rebound in cases, particularly among children. While the initial wave, dominated by A(H1N1)pdm09, appeared to subside in early January, the return to school has triggered a resurgence, raising fears of a potential second peak.
Flu Circulation remains Widespread Across France
The flu virus is currently active in all regions of France, with the exceptions of Mayotte, which is now post-epidemic, and Reunion, which has returned to baseline levels. Nationally, the rate of consultations for influenza-like illness reached 272 per 100,000 inhabitants as of the latest data, a slight increase from the previous week’s 250. SOS Médecins reports that influenza procedures represent 16.3% of all calls, categorized as a moderate level by Santé Publique France. Emergency rooms are also seeing continued activity, with 11,529 visits attributed to influenza syndrome, accounting for 3.1% of all visits. Notably, influenza remains the dominant cause of acute respiratory infections this season, considerably outpacing COVID-19 and RSV.
Intergenerational Divide: Children Lead the Rebound
A key dynamic shaping the current situation is a stark contrast between age groups. While adults have seen a decline in flu-related healthcare utilization – including fewer consultations with doctors, reduced SOS Médecins calls, and fewer emergency room visits – a clear rebound is emerging among children under the age of 15. Consultations are rising, virological positivity is climbing, and emergency room visits are increasing for this age group. This resurgence is linked to the start of the school year on January 6th, the resumption of virological positivity, the active circulation of A(H3N2), and the risk of intergenerational transmission following the return to school.
pdm09 continues to circulate. B viruses remain rare. However, within the A(H3N2) subtype, a specific variant – the K subclade – is particularly prevalent, accounting for 96% of sequenced viruses between weeks 48 and 52. Positivity rates confirm its intensity: 43.9% in community medicine,31.9% in medical biology laboratories, and 16.1% in hospitals.
the dominance of the K subclade is particularly concerning, as it is known to cause more severe illness in the elderly, aligning with the observed hospitalizations this winter.
Vaccination Efforts: Progress, But Still insufficient
As of December 31, 2025, vaccination coverage stands at 46.3% for individuals at risk and 53.3% for those aged 65 and over (including 29% with an enhanced vaccine). Coverage among those under 65 at risk is lower, at 27.1%. while vaccination rates are improved compared to last year, they still fall short of public health objectives. The vaccine’s effectiveness is estimated at 36.4% across all ages, but remains significantly higher than expected against A(H3N2), despite its divergent nature. Crucially, serious cases overwhelmingly affect unvaccinated individuals, according to intensive care data.
Second Wave or Seasonal Resurgence? the Uncertainty Continues
Epidemiologists remain cautious about predicting the future trajectory of the epidemic. Factors suggesting a potential second wave include the rebound in children, the resumption of virological positivity, the active circulation of A(H3N2), and the risk of intergenerational transmission following the return to school. Though, the decline in healthcare utilization among adults, decreasing hospitalizations and emergency room visits, and the fact that the epidemic has been well-established as December offer some counterarguments.
“Today we are in a zone of uncertainty,” one epidemiologist noted.”Children suggest an epidemic resumption, but the national trend is now based on developments over the next two weeks.”
It’s critically important to note that the K subclade of A(H3N2), while appearing more prevalent in children due to higher consultation rates, infects all age groups and is associated with more severe outcomes in the elderly. The coming weeks will be critical in determining whether France faces a second wave of influenza or simply a seasonal resurgence.
