Abstract

Background: Since 1985, two antigenically distinct lineages of influenza B viruses (Victoria-like and Yamagata-like) have circulated globally. Trivalent seasonal influenza vaccines contain two circulating influenza A strains but a single B strain and thus provide limited immunity against circulating B strains of the lineage not included in the vaccine. In this study, we describe the characteristics of influenza B viruses that caused respiratory illness in the population in Italy over 13 consecutive seasons of virological surveillance, and the match between the predominant influenza B lineage and the vaccine B lineage, in each season. Methods: From 2004 to 2017, 26,886 laboratory-confirmed influenza cases were registered in Italy, of which 18.7% were type B. Among them, the lineage of 2465 strains (49%) was retrieved or characterized in this study by a real-time RT-PCR assay and/or sequencing of the hemagglutinin (HA) gene. Results: Co-circulation of both B lineages was observed each season, although in different proportions every year. Overall, viruses of B/Victoria and B/Yamagata lineages caused 53.3 and 46.7% of influenza B infections, respectively. A higher proportion of infections with both lineages was detected in children, and there was a declining frequency of B/Victoria detections with age. A mismatch between the vaccine and the predominant influenza B lineage occurred in eight out of thirteen influenza seasons under study. Considering the seasons when B accounted for > 20% of all laboratory-confirmed influenza cases, a mismatch was observed in four out of six seasons. Phylogenetic analysis of the HA1 domain confirmed the co-circulation of both lineages and revealed a mixed circulation of distinct evolutionary viral variants, with different levels of match to the vaccine strains. Conclusions: This study contributes to the understanding of the circulation of influenza B viruses in Italy. We found a continuous co-circulation of both B lineages in the period 2004-2017, and determined that children were particularly vulnerable to Victoria-lineage influenza B virus infections. An influenza B lineage mismatch with the trivalent vaccine occurred in about two-thirds of cases.

Original languageEnglish
Article number990
JournalBMC Infectious Diseases
Volume19
Issue number1
DOIs
Publication statusPublished - Jan 1 2019

Keywords

  • Influenza B virus
  • Influenza virological surveillance
  • Italy
  • Vaccine match
  • Victoria lineage
  • Yamagata lineage

ASJC Scopus subject areas

  • Infectious Diseases

Cite this

Co-circulation of the two influenza B lineages during 13 consecutive influenza surveillance seasons in Italy, 2004-2017. / Italian Influenza Laboratory Network.

In: BMC Infectious Diseases, Vol. 19, No. 1, 990, 01.01.2019.

Research output: Contribution to journalReview article

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title = "Co-circulation of the two influenza B lineages during 13 consecutive influenza surveillance seasons in Italy, 2004-2017",
abstract = "Background: Since 1985, two antigenically distinct lineages of influenza B viruses (Victoria-like and Yamagata-like) have circulated globally. Trivalent seasonal influenza vaccines contain two circulating influenza A strains but a single B strain and thus provide limited immunity against circulating B strains of the lineage not included in the vaccine. In this study, we describe the characteristics of influenza B viruses that caused respiratory illness in the population in Italy over 13 consecutive seasons of virological surveillance, and the match between the predominant influenza B lineage and the vaccine B lineage, in each season. Methods: From 2004 to 2017, 26,886 laboratory-confirmed influenza cases were registered in Italy, of which 18.7{\%} were type B. Among them, the lineage of 2465 strains (49{\%}) was retrieved or characterized in this study by a real-time RT-PCR assay and/or sequencing of the hemagglutinin (HA) gene. Results: Co-circulation of both B lineages was observed each season, although in different proportions every year. Overall, viruses of B/Victoria and B/Yamagata lineages caused 53.3 and 46.7{\%} of influenza B infections, respectively. A higher proportion of infections with both lineages was detected in children, and there was a declining frequency of B/Victoria detections with age. A mismatch between the vaccine and the predominant influenza B lineage occurred in eight out of thirteen influenza seasons under study. Considering the seasons when B accounted for > 20{\%} of all laboratory-confirmed influenza cases, a mismatch was observed in four out of six seasons. Phylogenetic analysis of the HA1 domain confirmed the co-circulation of both lineages and revealed a mixed circulation of distinct evolutionary viral variants, with different levels of match to the vaccine strains. Conclusions: This study contributes to the understanding of the circulation of influenza B viruses in Italy. We found a continuous co-circulation of both B lineages in the period 2004-2017, and determined that children were particularly vulnerable to Victoria-lineage influenza B virus infections. An influenza B lineage mismatch with the trivalent vaccine occurred in about two-thirds of cases.",
keywords = "Influenza B virus, Influenza virological surveillance, Italy, Vaccine match, Victoria lineage, Yamagata lineage",
author = "{Italian Influenza Laboratory Network} and Simona Puzelli and Martino, {Angela Di} and Marzia Facchini and Concetta Fabiani and Laura Calzoletti and Mario, {Giuseppina Di} and Annapina Palmieri and Paola Affanni and Barbara Camilloni and Maria Chironna and Pierlanfranco D'Agaro and Simone Giannecchini and Elena Pariani and Caterina Serra and Caterina Rizzo and Antonino Bella and Isabella Donatelli and Castrucci, {Maria Rita} and Filippo Ansaldi and Rosaria Arvia and Alberta Azzi and Patrizia Bagnarelli and Fausto Baldanti and Capobianchi, {Maria Rosaria} and Silvana Castaldi and Colucci, {Maria Eugenia} and Cristina Galli and Valeria Ghisetti and Andrea Orsi and Elisabetta Pagani and Giorgio Pal{\`u} and Maurizio Sanguinetti and Riccardo Smeraglia and Fabio Tramuto and Francesco Vitale",
year = "2019",
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doi = "10.1186/s12879-019-4621-z",
language = "English",
volume = "19",
journal = "BMC Infectious Diseases",
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TY - JOUR

T1 - Co-circulation of the two influenza B lineages during 13 consecutive influenza surveillance seasons in Italy, 2004-2017

AU - Italian Influenza Laboratory Network

AU - Puzelli, Simona

AU - Martino, Angela Di

AU - Facchini, Marzia

AU - Fabiani, Concetta

AU - Calzoletti, Laura

AU - Mario, Giuseppina Di

AU - Palmieri, Annapina

AU - Affanni, Paola

AU - Camilloni, Barbara

AU - Chironna, Maria

AU - D'Agaro, Pierlanfranco

AU - Giannecchini, Simone

AU - Pariani, Elena

AU - Serra, Caterina

AU - Rizzo, Caterina

AU - Bella, Antonino

AU - Donatelli, Isabella

AU - Castrucci, Maria Rita

AU - Ansaldi, Filippo

AU - Arvia, Rosaria

AU - Azzi, Alberta

AU - Bagnarelli, Patrizia

AU - Baldanti, Fausto

AU - Capobianchi, Maria Rosaria

AU - Castaldi, Silvana

AU - Colucci, Maria Eugenia

AU - Galli, Cristina

AU - Ghisetti, Valeria

AU - Orsi, Andrea

AU - Pagani, Elisabetta

AU - Palù, Giorgio

AU - Sanguinetti, Maurizio

AU - Smeraglia, Riccardo

AU - Tramuto, Fabio

AU - Vitale, Francesco

PY - 2019/1/1

Y1 - 2019/1/1

N2 - Background: Since 1985, two antigenically distinct lineages of influenza B viruses (Victoria-like and Yamagata-like) have circulated globally. Trivalent seasonal influenza vaccines contain two circulating influenza A strains but a single B strain and thus provide limited immunity against circulating B strains of the lineage not included in the vaccine. In this study, we describe the characteristics of influenza B viruses that caused respiratory illness in the population in Italy over 13 consecutive seasons of virological surveillance, and the match between the predominant influenza B lineage and the vaccine B lineage, in each season. Methods: From 2004 to 2017, 26,886 laboratory-confirmed influenza cases were registered in Italy, of which 18.7% were type B. Among them, the lineage of 2465 strains (49%) was retrieved or characterized in this study by a real-time RT-PCR assay and/or sequencing of the hemagglutinin (HA) gene. Results: Co-circulation of both B lineages was observed each season, although in different proportions every year. Overall, viruses of B/Victoria and B/Yamagata lineages caused 53.3 and 46.7% of influenza B infections, respectively. A higher proportion of infections with both lineages was detected in children, and there was a declining frequency of B/Victoria detections with age. A mismatch between the vaccine and the predominant influenza B lineage occurred in eight out of thirteen influenza seasons under study. Considering the seasons when B accounted for > 20% of all laboratory-confirmed influenza cases, a mismatch was observed in four out of six seasons. Phylogenetic analysis of the HA1 domain confirmed the co-circulation of both lineages and revealed a mixed circulation of distinct evolutionary viral variants, with different levels of match to the vaccine strains. Conclusions: This study contributes to the understanding of the circulation of influenza B viruses in Italy. We found a continuous co-circulation of both B lineages in the period 2004-2017, and determined that children were particularly vulnerable to Victoria-lineage influenza B virus infections. An influenza B lineage mismatch with the trivalent vaccine occurred in about two-thirds of cases.

AB - Background: Since 1985, two antigenically distinct lineages of influenza B viruses (Victoria-like and Yamagata-like) have circulated globally. Trivalent seasonal influenza vaccines contain two circulating influenza A strains but a single B strain and thus provide limited immunity against circulating B strains of the lineage not included in the vaccine. In this study, we describe the characteristics of influenza B viruses that caused respiratory illness in the population in Italy over 13 consecutive seasons of virological surveillance, and the match between the predominant influenza B lineage and the vaccine B lineage, in each season. Methods: From 2004 to 2017, 26,886 laboratory-confirmed influenza cases were registered in Italy, of which 18.7% were type B. Among them, the lineage of 2465 strains (49%) was retrieved or characterized in this study by a real-time RT-PCR assay and/or sequencing of the hemagglutinin (HA) gene. Results: Co-circulation of both B lineages was observed each season, although in different proportions every year. Overall, viruses of B/Victoria and B/Yamagata lineages caused 53.3 and 46.7% of influenza B infections, respectively. A higher proportion of infections with both lineages was detected in children, and there was a declining frequency of B/Victoria detections with age. A mismatch between the vaccine and the predominant influenza B lineage occurred in eight out of thirteen influenza seasons under study. Considering the seasons when B accounted for > 20% of all laboratory-confirmed influenza cases, a mismatch was observed in four out of six seasons. Phylogenetic analysis of the HA1 domain confirmed the co-circulation of both lineages and revealed a mixed circulation of distinct evolutionary viral variants, with different levels of match to the vaccine strains. Conclusions: This study contributes to the understanding of the circulation of influenza B viruses in Italy. We found a continuous co-circulation of both B lineages in the period 2004-2017, and determined that children were particularly vulnerable to Victoria-lineage influenza B virus infections. An influenza B lineage mismatch with the trivalent vaccine occurred in about two-thirds of cases.

KW - Influenza B virus

KW - Influenza virological surveillance

KW - Italy

KW - Vaccine match

KW - Victoria lineage

KW - Yamagata lineage

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U2 - 10.1186/s12879-019-4621-z

DO - 10.1186/s12879-019-4621-z

M3 - Review article

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