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. 2015 Aug;9 Suppl 1(Suppl 1):3-12.
doi: 10.1111/irv.12319.

Epidemiological and virological characteristics of influenza B: results of the Global Influenza B Study

Saverio Caini  1 , Q Sue Huang  2 , Meral A Ciblak  3 , Gabriela Kusznierz  4 , Rhonda Owen  5 , Sonam Wangchuk  6 , Cláudio M P Henriques  7 , Richard Njouom  8 , Rodrigo A Fasce  9 , Hongjie Yu  10 , Luzhao Feng  10 , Maria Zambon  11 , Alexey W Clara  12 , Herman Kosasih  13 , Simona Puzelli  14 , Herve A Kadjo  15 , Gideon Emukule  16 , Jean-Michel Heraud  17 , Li Wei Ang  18 , Marietjie Venter  19   20 , Alla Mironenko  21 , Lynnette Brammer  22 , Le Thi Quynh Mai  23 , François Schellevis  1 , Stanley Plotkin  24 , John Paget  1 ; Global Influenza B Study
Collaborators, Affiliations

Epidemiological and virological characteristics of influenza B: results of the Global Influenza B Study

Saverio Caini et al. Influenza Other Respir Viruses. 2015 Aug.

Abstract

Introduction: Literature on influenza focuses on influenza A, despite influenza B having a large public health impact. The Global Influenza B Study aims to collect information on global epidemiology and burden of disease of influenza B since 2000.

Methods: Twenty-six countries in the Southern (n = 5) and Northern (n = 7) hemispheres and intertropical belt (n = 14) provided virological and epidemiological data. We calculated the proportion of influenza cases due to type B and Victoria and Yamagata lineages in each country and season; tested the correlation between proportion of influenza B and maximum weekly influenza-like illness (ILI) rate during the same season; determined the frequency of vaccine mismatches; and described the age distribution of cases by virus type.

Results: The database included 935 673 influenza cases (2000-2013). Overall median proportion of influenza B was 22·6%, with no statistically significant differences across seasons. During seasons where influenza B was dominant or co-circulated (>20% of total detections), Victoria and Yamagata lineages predominated during 64% and 36% of seasons, respectively, and a vaccine mismatch was observed in ≈25% of seasons. Proportion of influenza B was inversely correlated with maximum ILI rate in the same season in the Northern and (with borderline significance) Southern hemispheres. Patients infected with influenza B were usually younger (5-17 years) than patients infected with influenza A.

Conclusion: Influenza B is a common disease with some epidemiological differences from influenza A. This should be considered when optimizing control/prevention strategies in different regions and reducing the global burden of disease due to influenza.

Keywords: Burden of disease; Global Influenza B Study (GIBS); epidemiology; influenza; vaccination; vaccine mismatch.

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Figures

Figure 1
Figure 1
Countries participating in the Global Influenza B Study. April 2014.
Figure 2
Figure 2
Distribution of influenza seasons by proportion of influenza B cases and geographical area (Southern Hemisphere, intertropical belt and Northern Hemisphere). The Global Influenza B Study. April 2014. Purple bar presents median. Pink bars indicate 25% and 75% percentiles.
Figure 3
Figure 3
Proportion of influenza B and maximum influenza-like illness (ILI) rate (Z-score) during each season, by geographical area (Southern Hemisphere, intertropical belt and Northern Hemisphere). The Global Influenza B Study. April 2014.
See this image and copyright information in PMC

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