Key Points

Acute respiratory infections

• Peak activity in January at very high levels in the city and in hospitals, mainly due to the flu epidemic

Flu

• Early outbreak lasting 12 weeks

• Very high intensity in primary care, with nearly 3 million visits for flu-like illness

• Marked severity across all age groups, with 29,000 hospitalizations following visits to the emergency room for influenza or influenza-like illness

• Significant impact of the epidemic in terms of mortality

• Unusual co-circulation of the three viruses A(H1N1)pdm09, A(H3N2), and B/Victoria

• Vaccination coverage estimated at 53.7% among those aged 65 and older, and 25.3% among at-risk individuals under 65, relatively stable compared to 2023–2024

Bronchiolitis

• In mainland France, an epidemic from mid-November 2024 (Week 47) to mid-January 2025 (Week 2)

• Epidemic dynamics generally comparable to those of epidemics preceding the COVID-19 pandemic

• Short-duration (8 weeks) and low-intensity epidemic, less severe than those preceding or following the emergence of COVID-19, particularly among infants under 3 months of age

COVID-19

• Activity at low levels during the 2024–25 winter season

• Decline in indicators since the peaks observed in July and September 2024

• Predominant circulation of the KP.3.1.1 variant between September and November, and XEC (KS.1.1/KP.3.3 recombinant) since late November 2024