Global patterns of seasonal influenza activity, duration of activity and virus (sub)type circulation from 2010 to 2020.
duration of epidemics
influenza
influenza virus circulation
influenza virus type, subtype, and lineage
seasonal influenza
timing of epidemic peak
Journal
Influenza and other respiratory viruses
ISSN: 1750-2659
Titre abrégé: Influenza Other Respir Viruses
Pays: England
ID NLM: 101304007
Informations de publication
Date de publication:
07 2022
07 2022
Historique:
received:
01
01
2022
accepted:
18
01
2022
pubmed:
26
2
2022
medline:
11
6
2022
entrez:
25
2
2022
Statut:
ppublish
Résumé
Seasonal influenza viruses undergo unpredictable changes, which may lead to antigenic mismatch between circulating and vaccine strains and to a reduced vaccine effectiveness. A continuously updated knowledge of influenza strain circulation and seasonality is essential to optimize the effectiveness of influenza vaccination campaigns. We described the global epidemiology of influenza between the 2009 A(H1N1)p and the 2020 COVID-19 pandemic. Influenza virological surveillance data were obtained from the WHO-FluNet database. We determined the median proportion of influenza cases caused by the different influenza virus types, subtypes, and lineages; the typical timing of the epidemic peak; and the median duration of influenza epidemics (applying the annual average percentage method with a 75% threshold). We included over 4.6 million influenza cases from 149 countries. The median proportion of influenza cases caused by type A viruses was 75.5%, highest in the Southern hemisphere (81.6%) and lowest in the intertropical belt (73.0%), and ranged across seasons between 60.9% in 2017 and 88.7% in 2018. Epidemic peaks typically occurred during winter months in Northern and Southern hemisphere countries, while much more variability emerged in tropical countries. Influenza epidemics lasted a median of 25 weeks (range 8-42) in countries lying between 30°N and 26°S, and a median of 9 weeks (range 5-25) in countries outside this latitude range. This work will establish an important baseline to better understand factors that influence seasonal influenza dynamics and how COVID-19 may have affected seasonal activity and influenza virus types, subtypes, and lineages circulation patterns.
Sections du résumé
BACKGROUND
Seasonal influenza viruses undergo unpredictable changes, which may lead to antigenic mismatch between circulating and vaccine strains and to a reduced vaccine effectiveness. A continuously updated knowledge of influenza strain circulation and seasonality is essential to optimize the effectiveness of influenza vaccination campaigns. We described the global epidemiology of influenza between the 2009 A(H1N1)p and the 2020 COVID-19 pandemic.
METHODS
Influenza virological surveillance data were obtained from the WHO-FluNet database. We determined the median proportion of influenza cases caused by the different influenza virus types, subtypes, and lineages; the typical timing of the epidemic peak; and the median duration of influenza epidemics (applying the annual average percentage method with a 75% threshold).
RESULTS
We included over 4.6 million influenza cases from 149 countries. The median proportion of influenza cases caused by type A viruses was 75.5%, highest in the Southern hemisphere (81.6%) and lowest in the intertropical belt (73.0%), and ranged across seasons between 60.9% in 2017 and 88.7% in 2018. Epidemic peaks typically occurred during winter months in Northern and Southern hemisphere countries, while much more variability emerged in tropical countries. Influenza epidemics lasted a median of 25 weeks (range 8-42) in countries lying between 30°N and 26°S, and a median of 9 weeks (range 5-25) in countries outside this latitude range.
CONCLUSIONS
This work will establish an important baseline to better understand factors that influence seasonal influenza dynamics and how COVID-19 may have affected seasonal activity and influenza virus types, subtypes, and lineages circulation patterns.
Identifiants
pubmed: 35212157
doi: 10.1111/irv.12969
pmc: PMC9178051
doi:
Substances chimiques
Influenza Vaccines
0
Types de publication
Journal Article
Research Support, Non-U.S. Gov't
Langues
eng
Sous-ensembles de citation
IM
Pagination
696-706Informations de copyright
© 2022 The Authors. Influenza and Other Respiratory Viruses published by John Wiley & Sons Ltd.
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