Antigenic Divergence from the Seasonal Vaccine of the Influenza Virus Strains Circulating in Romania During Three Successive Seasons (2021–2024)

Influenza viruses continue to be an important public health threat. Vaccination is the most effective measure to control the influenza virus circulation. However, these viruses are continuously evolving through antigenic drift/shift, and thus the vaccine efficiency is affected. The aim of this study...

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Main Authors: Ovidiu Vlaicu, Leontina Banica, Robert Hohan, Marius Surleac, Dragoş Florea, Victor Daniel Miron, Andreea Tudor, Oana Săndulescu, Anca Cristina Drăgănescu, Dan Oțelea, Simona Paraschiv
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Language:English
Published: MDPI AG 2024-11-01
Series:Microorganisms
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Online Access:https://www.mdpi.com/2076-2607/12/11/2363
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author Ovidiu Vlaicu
Leontina Banica
Robert Hohan
Marius Surleac
Dragoş Florea
Victor Daniel Miron
Andreea Tudor
Oana Săndulescu
Anca Cristina Drăgănescu
Dan Oțelea
Simona Paraschiv
author_facet Ovidiu Vlaicu
Leontina Banica
Robert Hohan
Marius Surleac
Dragoş Florea
Victor Daniel Miron
Andreea Tudor
Oana Săndulescu
Anca Cristina Drăgănescu
Dan Oțelea
Simona Paraschiv
author_sort Ovidiu Vlaicu
collection DOAJ
description Influenza viruses continue to be an important public health threat. Vaccination is the most effective measure to control the influenza virus circulation. However, these viruses are continuously evolving through antigenic drift/shift, and thus the vaccine efficiency is affected. The aim of this study was to characterize the viral strains circulating in Romania, in a population with declining vaccination coverage, during the last three cold seasons by evaluating the hemagglutinin antigenic relatedness to the vaccine strains. All the available sequences collected between August 2021 and June 2024 were analyzed by using phylogenetic analysis and the P<sub>epitope</sub> model to predict vaccine efficacy. The results showed that the 2021/2022 influenza season was dominated by the circulation of highly diverse clades of A(H3N2) viruses with high mutational divergence as compared to the vaccine strain, which might contribute to the reduction in vaccine efficacy. During the 2022/2023 influenza season, both influenza A and B viruses were reported, with few antigenic site mutations. The 2023/2024 influenza season was dominated by the circulation of influenza A viruses: A/H1N1pdm09 clade 6B.1A.5a.2a and A/H3N2 clade 2a.3a.1. The clade 2a.3a.1 also showed high variability when compared to the vaccine strain, presumably leading to reduced vaccine efficacy. This study illustrates the high diversity of influenza viruses circulating in a population with low vaccination coverage during the previous cold seasons. The viral diversity impacted vaccine efficacy, hence the need for public health programs to increase vaccine uptake and improve vaccine formulation in order to limit viral transmission.
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spelling doaj-art-a42e11d5ddda40ae8cb7799e9374dde72025-08-20T01:54:03ZengMDPI AGMicroorganisms2076-26072024-11-011211236310.3390/microorganisms12112363Antigenic Divergence from the Seasonal Vaccine of the Influenza Virus Strains Circulating in Romania During Three Successive Seasons (2021–2024)Ovidiu Vlaicu0Leontina Banica1Robert Hohan2Marius Surleac3Dragoş Florea4Victor Daniel Miron5Andreea Tudor6Oana Săndulescu7Anca Cristina Drăgănescu8Dan Oțelea9Simona Paraschiv10National Institute for Infectious Diseases “Prof. Dr. Matei Bals”, 021105 Bucharest, RomaniaNational Institute for Infectious Diseases “Prof. Dr. Matei Bals”, 021105 Bucharest, RomaniaNational Institute for Infectious Diseases “Prof. Dr. Matei Bals”, 021105 Bucharest, RomaniaNational Institute for Infectious Diseases “Prof. Dr. Matei Bals”, 021105 Bucharest, RomaniaNational Institute for Infectious Diseases “Prof. Dr. Matei Bals”, 021105 Bucharest, RomaniaNational Institute for Infectious Diseases “Prof. Dr. Matei Bals”, 021105 Bucharest, RomaniaNational Institute for Infectious Diseases “Prof. Dr. Matei Bals”, 021105 Bucharest, RomaniaNational Institute for Infectious Diseases “Prof. Dr. Matei Bals”, 021105 Bucharest, RomaniaNational Institute for Infectious Diseases “Prof. Dr. Matei Bals”, 021105 Bucharest, RomaniaNational Institute for Infectious Diseases “Prof. Dr. Matei Bals”, 021105 Bucharest, RomaniaNational Institute for Infectious Diseases “Prof. Dr. Matei Bals”, 021105 Bucharest, RomaniaInfluenza viruses continue to be an important public health threat. Vaccination is the most effective measure to control the influenza virus circulation. However, these viruses are continuously evolving through antigenic drift/shift, and thus the vaccine efficiency is affected. The aim of this study was to characterize the viral strains circulating in Romania, in a population with declining vaccination coverage, during the last three cold seasons by evaluating the hemagglutinin antigenic relatedness to the vaccine strains. All the available sequences collected between August 2021 and June 2024 were analyzed by using phylogenetic analysis and the P<sub>epitope</sub> model to predict vaccine efficacy. The results showed that the 2021/2022 influenza season was dominated by the circulation of highly diverse clades of A(H3N2) viruses with high mutational divergence as compared to the vaccine strain, which might contribute to the reduction in vaccine efficacy. During the 2022/2023 influenza season, both influenza A and B viruses were reported, with few antigenic site mutations. The 2023/2024 influenza season was dominated by the circulation of influenza A viruses: A/H1N1pdm09 clade 6B.1A.5a.2a and A/H3N2 clade 2a.3a.1. The clade 2a.3a.1 also showed high variability when compared to the vaccine strain, presumably leading to reduced vaccine efficacy. This study illustrates the high diversity of influenza viruses circulating in a population with low vaccination coverage during the previous cold seasons. The viral diversity impacted vaccine efficacy, hence the need for public health programs to increase vaccine uptake and improve vaccine formulation in order to limit viral transmission.https://www.mdpi.com/2076-2607/12/11/2363influenza virusvaccine efficacyantigenic relatednesshemagglutinin sequencesinfluenza cladesphylogenetic analysis
spellingShingle Ovidiu Vlaicu
Leontina Banica
Robert Hohan
Marius Surleac
Dragoş Florea
Victor Daniel Miron
Andreea Tudor
Oana Săndulescu
Anca Cristina Drăgănescu
Dan Oțelea
Simona Paraschiv
Antigenic Divergence from the Seasonal Vaccine of the Influenza Virus Strains Circulating in Romania During Three Successive Seasons (2021–2024)
Microorganisms
influenza virus
vaccine efficacy
antigenic relatedness
hemagglutinin sequences
influenza clades
phylogenetic analysis
title Antigenic Divergence from the Seasonal Vaccine of the Influenza Virus Strains Circulating in Romania During Three Successive Seasons (2021–2024)
title_full Antigenic Divergence from the Seasonal Vaccine of the Influenza Virus Strains Circulating in Romania During Three Successive Seasons (2021–2024)
title_fullStr Antigenic Divergence from the Seasonal Vaccine of the Influenza Virus Strains Circulating in Romania During Three Successive Seasons (2021–2024)
title_full_unstemmed Antigenic Divergence from the Seasonal Vaccine of the Influenza Virus Strains Circulating in Romania During Three Successive Seasons (2021–2024)
title_short Antigenic Divergence from the Seasonal Vaccine of the Influenza Virus Strains Circulating in Romania During Three Successive Seasons (2021–2024)
title_sort antigenic divergence from the seasonal vaccine of the influenza virus strains circulating in romania during three successive seasons 2021 2024
topic influenza virus
vaccine efficacy
antigenic relatedness
hemagglutinin sequences
influenza clades
phylogenetic analysis
url https://www.mdpi.com/2076-2607/12/11/2363
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