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. 2023 Jan 5;49(1):10-14.
doi: 10.14745/ccdr.v49i01a03.

National influenza mid-season report, 2022-2023: A rapid and early epidemic onset

Myriam Ben Moussa  1 , Steven Buckrell  1 , Abbas Rahal  1 , Kara Schmidt  1 , Liza Lee  1 , Nathalie Bastien  2 , Christina Bancej  1
Affiliations

National influenza mid-season report, 2022-2023: A rapid and early epidemic onset

Myriam Ben Moussa et al. Can Commun Dis Rep. .

Abstract

Canada's 2022-2023 national influenza epidemic was declared in epidemiological week 43 (week ending October 29, 2022), relatively early in comparison to historical seasons. This year marks the return to pre-pandemic-like influenza circulation, following the brief and delayed influenza epidemic declared in the spring of the 2021-2022 season. To date this season, 59,459 detections of influenza have been reported out of 456,536 tests; both values exceeding historical averages. This epidemic is being fundamentally driven by influenza A, with influenza A(H3N2) accounting for 94% of subtyped detections. This season to date has had a significant impact on adolescents and young children, with a high proportion of detections occurring in those aged 0-19 years (42%). Provinces and territories have reported higher than usual influenza-associated hospitalizations, intensive care unit admissions, and deaths in comparison with previous seasons; in particular, paediatric hospitalization incidence was persistently far above historical peak levels for several weeks. The return of seasonal influenza circulation highlights the importance of sustained vigilance with regard to influenza and employment of available mitigation measures, especially of annual seasonal influenza vaccination.

Keywords: Canada; epidemic; influenza; influenza A(H3N2); paediatric; surveillance.

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Conflict of interest statement

Competing interests: None.

Figures

Figure 1
Figure 1
Number of positive influenza tests and percentage of tests positive, by type, subtype and report week, Canada, 2022–2023 influenza season to date, weeks 35 to 52
Figure 2
Figure 2
Number of paediatrica hospitalizations reported by the Immunization Monitoring Program Active network, by age group, by week, Canada, 2022–2023 influenza season to date, weeks 35 to 52b a 16 years of age and younger b Shaded area represents the maximum and minimum numbers of paediatric hospitalizations reported by Immunization Monitoring Program Active (IMPACT) by week from seasons 2014–2015 to 2019–2020
See this image and copyright information in PMC

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