Diversity in the circulation of influenza a(H3n2) viruses in the northern hemisphere in the 2018–19 season

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

Research output: Contribution to journalArticlepeer-review


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.

Original languageEnglish
Article number375
Issue number4
StatePublished - 13 Apr 2021

Bibliographical note

Publisher Copyright:
© 2021 by the authors. Licensee MDPI, Basel, Switzerland.


  • Circulation
  • Clade
  • Influenza A
  • Vaccine

ASJC Scopus subject areas

  • Drug Discovery
  • Infectious Diseases
  • Pharmacology (medical)
  • Pharmacology
  • Immunology


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