Recommended composition of influenza virus vaccines for use in the 2022-2023 northern hemisphere influenza season/Composition recommandee des vaccins antigrippaux pour la saison grippale 2022-2023 dans l'hemisphere Nord.

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Date: Mar. 25, 2022
From: Weekly Epidemiological Record(Vol. 97, Issue 12)
Publisher: World Health Organization
Document Type: Article
Length: 7,581 words
Lexile Measure: 1670L

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February 2022

WHO convenes technical consultations (1) in February and September each year to recommend viruses for inclusion in influenza vaccines (2) for the northern hemisphere (NH) and southern hemisphere (SH) influenza seasons, respectively. This recommendation relates to the influenza vaccines for use in the NH 2022-202 (3) influenza season. A recommendation will be made in September 2022 relating to vaccines that will be used for the SH 2023 influenza season. For countries in tropical and subtropical regions, WHO recommendations for influenza vaccine composition (NH or SH) are available on the WHO Global Influenza Programme website. (3)

Seasonal influenza activity

Public health and laboratory responses to the COVID-19 pandemic disrupted the influenza surveillance and/or reporting activities to varying extents in many countries. SARS-CoV-2 mitigation strategies including restrictions on travel, use of respiratory protection, and social-distancing measures in most countries continue to result in decreased influenza transmission. Between September 2021 and January 2022, low numbers of influenza detections were reported and fewer viruses have been available for characterization in comparison to similar time periods prior to the COVID-19 pandemic. Nevertheless, epidemics were reported by a number of countries and regions, with higher detections of influenza activity in the 2021-2022 season than in the 2020-2021 influenza season.

Between September 2021 and January 2022, influenza A(H1N1)pdm09, A(H3N2) and influenza B viruses circulated in low numbers and the relative proportions of the viruses circulating varied among reporting countries. Globally, since September 2021, most influenza virus detections were reported by countries in the temperate zone of the northern hemisphere and countries in the tropics and subtropics. Overall, percent positivity of influenza viruses during this period was <3%. In contrast, the average percent positivity during similar reporting periods prior to the COVID-19 pandemic (2017-2020) was 17%.

In the temperate zone of the northern hemisphere, influenza activity was lower than in the corresponding reporting periods before the COVID-19 pandemic. However, compared with the 2020-2021 influenza season, countries reported increases of over 2.5-fold in the number of specimens tested for influenza and over 35-fold in the number of influenza viruses detected. Influenza A was predominant in most countries while influenza B predominated in a few countries in the temperate zone of the northern hemisphere. In north Africa, influenza virus detections were reported by Algeria, Egypt, Morocco and Tunisia with a predominance of A(H3N2). In Asia, both influenza A and B viruses were detected in most reporting countries except in China where influenza B predominated. Of the subtyped influenza A viruses, A(H3N2) predominated. In Afghanistan, Iraq, Islamic Republic of Iran, Kazakhstan, Kyrgyzstan, Lebanon, Mongolia, Syrian Arab Republic and Uzbekistan, only A(H3N2) viruses were reported. Influenza A(H3N2) predominated in most countries in Europe and North America with influenza B viruses also detected. In France, influenza A(H1N1)pdm09 predominated.

Influenza activity in tropical and subtropical countries was lower than in the corresponding reporting periods before the COVID-19 pandemic, with co-circulation of influenza A(H1N1)pdm09, A(H3N2) and influenza B viruses. In the tropical countries of Africa, most influenza detections were reported from central, east...

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Gale Document Number: GALE|A699755787