title: Improving influenza virological surveillance in Europe: strain-based reporting of antigenic and genetic characterisation data, 11 European countries, influenza season 2013/14.
abstract: Influenza antigenic and genetic characterisation data are crucial for influenza vaccine composition decision making. Previously, aggregate data were reported to the European Centre for Disease Prevention and Control by European Union/European Economic Area (EU/EEA) countries. A system for collecting case-specific influenza antigenic and genetic characterisation data was established for the 2013/14 influenza season. In a pilot study, 11 EU/EEA countries reported through the new mechanism. We demonstrated feasibility of reporting strain-based antigenic and genetic data and ca 10% of influenza virus-positive specimens were selected for further characterisation. Proportions of characterised virus (sub)types were similar to influenza virus circulation levels. The main genetic clades were represented by A/StPetersburg/27/2011(H1N1)pdm09 and A/Texas/50/2012(H3N2). A(H1N1)pdm09 viruses were more prevalent in age groups (by years) < 1 (65%; p = 0.0111), 20-39 (50%; p = 0.0046) and 40-64 (55%; p = 0.00001) while A(H3N2) viruses were most prevalent in those ≥ 65 years (62%*; p = 0.0012). Hospitalised patients in the age groups 6-19 years (67%; p = 0.0494) and ≥ 65 years (52%; p = 0.0005) were more frequently infected by A/Texas/50/2012 A(H3N2)-like viruses compared with hospitalised cases in other age groups. Strain-based reporting enabled deeper understanding of influenza virus circulation among hospitalised patients and substantially improved the reporting of virus characterisation data. Therefore, strain-based reporting of readily available data is recommended to all reporting countries within the EU/EEA.
authors.affiliation: European Centre for Disease Prevention and Control (ECDC), Stockholm, Sweden.
authors.forename: Eeva
authors.initials: E
authors.lastname: Broberg
authors.forename: Olav
authors.initials: O
authors.lastname: Hungnes
authors.forename: Brunhilde
authors.initials: B
authors.lastname: Schweiger
authors.forename: Katarina
authors.initials: K
authors.lastname: Prosenc
authors.forename: Rod
authors.initials: R
authors.lastname: Daniels
authors.forename: Raquel
authors.initials: R
authors.lastname: Guiomar
authors.forename: Niina
authors.initials: N
authors.lastname: Ikonen
authors.forename: Athanasios
authors.initials: A
authors.lastname: Kossyvakis
authors.forename: Francisco
authors.initials: F
authors.lastname: Pozo
authors.forename: Simona
authors.initials: S
authors.lastname: Puzelli
authors.forename: Isabelle
authors.initials: I
authors.lastname: Thomas
authors.forename: Allison
authors.initials: A
authors.lastname: Waters
authors.forename: Åsa
authors.initials: Å
authors.lastname: Wiman
authors.forename: Adam
authors.initials: A
authors.lastname: Meijer
mesh_terms: D000293:Adolescent; D000328:Adult; D017677:Age Distribution; D000368:Aged; D002648:Child; D002675:Child, Preschool; D062665:Epidemiological Monitoring; D005060:Europe / Q000453:epidemiology; D005062:European Union; D005240:Feasibility Studies; D006385:Hemagglutination Inhibition Tests; D006760:Hospitalization / Q000706:statistics & numerical data; D006801:Humans; D053118:Influenza A Virus, H1N1 Subtype / Q000235:genetics* / Q000276:immunology* / Q000302:isolation & purification; D053122:Influenza A Virus, H3N2 Subtype / Q000235:genetics* / Q000276:immunology* / Q000302:isolation & purification; D007252:Influenza Vaccines / Q000008:administration & dosage / Q000276:immunology*; D007251:Influenza, Human / Q000453:epidemiology / Q000517:prevention & control / Q000821:virology*; D008875:Middle Aged; D012367:RNA, Viral / Q000235:genetics; D012621:Seasons; D018571:Sentinel Surveillance; D017422:Sequence Analysis, DNA; D017678:Sex Distribution; D014611:Vaccination / Q000706:statistics & numerical data; D055815:Young Adult
chemical_list: D007252:Influenza Vaccines; D012367:RNA, Viral
keywords: age; genetic clade; hospitalisation; influenza; influenza season