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. 2017 Sep 15;216(6):697-702.
doi: 10.1093/infdis/jix393.

Age-Related Differences in Influenza B Infection by Lineage in a Community-Based Sentinel System, 2010-2011 to 2015-2016, Canada

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Age-Related Differences in Influenza B Infection by Lineage in a Community-Based Sentinel System, 2010-2011 to 2015-2016, Canada

Danuta M Skowronski et al. J Infect Dis. .

Abstract

Age-related differences in influenza B lineage detection were explored in the community-based Canadian Sentinel Practitioner Surveillance Network (SPSN) from 2010-2011 to 2015-2016. Whereas >80% of B(Victoria) cases were <40 years old, B(Yamagata) cases showed a bimodal age distribution with 27% who were <20 years old and 61% who were 30-64 years old, but with a notable gap in cases between 20 and 29 years old (4%). Overall, the median age was 20 years lower for B(Victoria) vs B(Yamagata) cases (20 vs 40 years; P < .01). Additional phylodynamic and immuno-epidemiological research is needed to understand age-related variation in influenza B risk by lineage, with potential implications for prevention and control across the lifespan.

Keywords: age; birth cohort effects; influenza B lineage; influenza B virus; risk.

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Figures

Figure 1.
Figure 1.
Median age by influenza B lineage (A) and percentage distribution of influenza B cases by lineage and season (B), Canadian Sentinel Practitioner Surveillance Network, 2010–2011 to 2015–2016. *Sequencing and lineage-specific reverse-transcription polymerase chain reaction assay were not conducted on influenza B detections during the 2010–2011 season; lineage-level characterization was based only upon hemagglutination inhibition assay among isolates submitted to Canada’s National Microbiology Laboratory, accounting for a greater proportion of viruses with unknown lineage that season.
Figure 2.
Figure 2.
Percentage distribution of influenza B(Victoria) cases (A) and influenza B(Yamagata) cases (B) and test-negative controls by single-year age group, Canadian Sentinel Practitioner Surveillance Network (SPSN), 2010–2011 to 2015–2016. The percentage of all cases of the specified influenza B lineage belonging to a given age (in years) is displayed as a bar graph; the same information for test-negative controls is superimposed as a dotted line for comparison purposes to indicate the sampling distribution by age in the overall SPSN sample.

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