tetano
Editor, Senior Moderator
BMC Infect Dis. 2019 Nov 21;19(1):990. doi: 10.1186/s12879-019-4621-z. [h=1]Co-circulation of the two influenza B lineages during 13 consecutive influenza surveillance seasons in Italy, 2004-2017.[/h]
Puzelli S[SUP]1[/SUP], Di Martino A[SUP]2[/SUP], Facchini M[SUP]2[/SUP], Fabiani C[SUP]2[/SUP], Calzoletti L[SUP]2[/SUP], Di Mario G[SUP]2[/SUP], Palmieri A[SUP]2[/SUP], Affanni P[SUP]3[/SUP], Camilloni B[SUP]4[/SUP], Chironna M[SUP]5[/SUP], D'Agaro P[SUP]6[/SUP], Giannecchini S[SUP]7[/SUP], Pariani E[SUP]8[/SUP], Serra C[SUP]9[/SUP], Rizzo C[SUP]2[/SUP], Bella A[SUP]2[/SUP], Donatelli I[SUP]2[/SUP], Castrucci MR[SUP]2[/SUP]; Italian Influenza Laboratory Network.
[h=3]Collaborators (17)[/h]
[h=3]Author information[/h] 1 Department of Infectious Diseases, Istituto Superiore di Sanit? (ISS), Viale Regina Elena 299, Rome, Italy. simona.puzelli@iss.it. 2 Department of Infectious Diseases, Istituto Superiore di Sanit? (ISS), Viale Regina Elena 299, Rome, Italy. 3 University of Parma, Parma, Italy. 4 University of Perugia, Perugia, Italy. 5 Department of Biomedical Science and Human Oncology, University of Bari, Bari, Italy. 6 University of Trieste, Trieste, Italy. 7 University of Florence, Florence, Italy. 8 Department of Biomedical Sciences for Health, University of Milan, Milan, Italy. 9 University of Sassari, Sassari, Italy.
[h=3]Abstract[/h] [h=4]BACKGROUND:[/h] 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.
[h=4]METHODS:[/h] 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.
[h=4]RESULTS:[/h] 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.
[h=4]CONCLUSIONS:[/h] 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.
[h=4]KEYWORDS:[/h] Influenza B virus; Influenza virological surveillance; Italy; Vaccine match; Victoria lineage; Yamagata lineage
PMID: 31752738 DOI: 10.1186/s12879-019-4621-z
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Puzelli S[SUP]1[/SUP], Di Martino A[SUP]2[/SUP], Facchini M[SUP]2[/SUP], Fabiani C[SUP]2[/SUP], Calzoletti L[SUP]2[/SUP], Di Mario G[SUP]2[/SUP], Palmieri A[SUP]2[/SUP], Affanni P[SUP]3[/SUP], Camilloni B[SUP]4[/SUP], Chironna M[SUP]5[/SUP], D'Agaro P[SUP]6[/SUP], Giannecchini S[SUP]7[/SUP], Pariani E[SUP]8[/SUP], Serra C[SUP]9[/SUP], Rizzo C[SUP]2[/SUP], Bella A[SUP]2[/SUP], Donatelli I[SUP]2[/SUP], Castrucci MR[SUP]2[/SUP]; Italian Influenza Laboratory Network.
[h=3]Collaborators (17)[/h]
[h=3]Author information[/h] 1 Department of Infectious Diseases, Istituto Superiore di Sanit? (ISS), Viale Regina Elena 299, Rome, Italy. simona.puzelli@iss.it. 2 Department of Infectious Diseases, Istituto Superiore di Sanit? (ISS), Viale Regina Elena 299, Rome, Italy. 3 University of Parma, Parma, Italy. 4 University of Perugia, Perugia, Italy. 5 Department of Biomedical Science and Human Oncology, University of Bari, Bari, Italy. 6 University of Trieste, Trieste, Italy. 7 University of Florence, Florence, Italy. 8 Department of Biomedical Sciences for Health, University of Milan, Milan, Italy. 9 University of Sassari, Sassari, Italy.
[h=3]Abstract[/h] [h=4]BACKGROUND:[/h] 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.
[h=4]METHODS:[/h] 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.
[h=4]RESULTS:[/h] 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.
[h=4]CONCLUSIONS:[/h] 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.
[h=4]KEYWORDS:[/h] Influenza B virus; Influenza virological surveillance; Italy; Vaccine match; Victoria lineage; Yamagata lineage
PMID: 31752738 DOI: 10.1186/s12879-019-4621-z
Free full text