TY - JOUR
T1 - Co-circulation of the two influenza B lineages during 13 consecutive influenza surveillance seasons in Italy, 2004-2017
AU - Puzelli, Simona
AU - Di Martino, Angela
AU - Facchini, Marzia
AU - Fabiani, Concetta
AU - Calzoletti, Laura
AU - Di Mario, Giuseppina
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 - Palu, Giorgio
AU - Sanguinetti, Maurizio
AU - Smeraglia, Riccardo
AU - Tramuto, Fabio
AU - Vitale, Francesco
AU - Network, Italian Influenza Lab
PY - 2019/11/21
Y1 - 2019/11/21
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 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 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 > 20confirmed 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 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 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 > 20confirmed 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 virological surveillance
KW - Influenza B virus
KW - Victoria lineage
KW - Yamagata lineage
KW - Vaccine match
KW - Italy
U2 - 10.1186/s12879-019-4621-z
DO - 10.1186/s12879-019-4621-z
M3 - Article
SN - 1471-2334
VL - 19
JO - BMC Infectious Diseases
JF - BMC Infectious Diseases
IS - 1
ER -