Diversity in the Circulation of Influenza A(H3N2) Viruses in the Northern Hemisphere in the 2018–19 Season

Rakefet Pando,Yaron Drori,Nehemya Friedman,Shahar Stern,Ital Nemet,Neta S Zuckerman,Lital Keinan-Boker,Ella Mendelson,Aharona Glatman-Freedman,Michal Mandelboim,John W Mccauley,Rodney S Daniels,Hanna Sefty

doi:10.3390/vaccines9040375

Abstract

While vaccination is considered the most effective means to prevent influenza infection, its seasonal effectiveness varies, depending on the circulating influenza strains. Here, we characterized the circulation of influenza strains in October-2018 and March-2019 around the world. For this, we used nasopharyngeal samples collected from outpatient and hospitalized patients in Israel and data reported in ECDC, CDC, and WHO databases. Influenza A(H3N2) was dominant in Israel, while in Europe, Asia, and USA, A(H1N1)pdm09 virus circulated first, and then the A(H3N2) virus also appeared. Phylogenetic analysis indicated that A(H3N2) viruses circulating in Israel belonged to clade-3C.3a, while in Europe, Asia, and USA, A(H3N2) viruses belonged to subclade-3C.2a1, but were later replaced by clade-3C.3a viruses in USA. The vaccine A(H3N2) components of that year, A/Singapore/INFIMH-16-0019/2016-(H3N2)-like-viruses, belonged to clade-3C.2a1. The circulation of different influenza subtypes and clades of A(H3N2) viruses in a single season highlights the need for universal influenza vaccines.

Highlights

Influenza viruses cause contagious respiratory disease [1] and are classified as types A, B, and C, with the first two significantly impacting human health each year [2]
The composition of the annual vaccines follows recommendations developed by the World Health Organization (WHO), based on worldwide surveillance conducted by the Global Influenza Surveillance and Response System (GISRS) [13]
The analysis showed that the circulating viruses in Israel in 2018–19 belonged to clade-3C.3a, while the A/Singapore/INFIMH-160019/2016-like vaccine virus belonged to clade-3C.2a, subclade-3C.2a1

Summary

Introduction

Influenza viruses cause contagious respiratory disease [1] and are classified as types A, B, and C, with the first two significantly impacting human health each year [2]. Type A viruses are divided into subtypes determined by their hemagglutinins (HA) and neuraminidases (NA), with A(H3N2) and A(H1N1)pdm subtypes currently circulating in humans [1,3]. While in most years a single subtype predominates, the two type A virus subtypes can co-circulate [4,5]. For the 2017–18 season, the vaccine virus recommendations for the Northern hemisphere were A/Michigan/45/2015 (H1N1) pdm09-like; A/Hong Kong/4801/2014 (H3N2)-like; B/Brisbane/60/2008-like (B/Victoria/2/87 lineage); and B/Phuket/3073/2013like (B/Yamagata/16/88 lineage) [16]. For the 2018–19 season, two vaccine component changes were recommended to an A/Singapore/INFIMH-16-0019/2016 (H3N2)-like virus and a B/Colorado/06/2017-like virus (B/Victoria/2/87 lineage) [17]

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