Key Points

Acute respiratory infections

• An epidemic of lesser intensity than the 2022–2023 season.

• In emergency departments, a larger-scale outbreak than the previous season.

Bronchiolitis

• An epidemic lasting 10 weeks, from late October 2023 to early January 2024.

• High intensity, but nevertheless lower than in the 2022–2023 season.

• Hospital impact defined as moderate; however, bronchiolitis accounted for nearly 48% of hospitalizations following emergency department visits at the peak of the outbreak.

• The proportion of infants under 3 months of age among hospitalized cases was lower than in previous seasons (34%).

Influenza

• Epidemic phase lasting 10 weeks, from late December 2023 to early March 2024.

• Epidemic peak later than the previous season (late January 2024).

• Moderate scope and high intensity, lower than in the 2022–2023 season.

• Hospital impact defined as high, with 1,405 hospitalizations following emergency department visits during the epidemic period.

COVID-19

• Two resurgences observed during the surveillance period (from early September 2023 to mid-April 2024) with circulation of Omicron recombinants followed by the JN.1 variant.

• A resurgence was observed from November to December 2023, with a scale and intensity similar to that of the winter of 2022–2023.

• People aged 65 and older accounted for the largest proportion of emergency department visits and hospitalizations following emergency department visits.