title: Influenza vaccine effectiveness in Italy: Age, subtype-specific and vaccine type estimates 2014/15 season.
abstract: The 2014/15 influenza season in Europe was characterised by the circulation of influenza A(H3N2) viruses with an antigenic and genetic mismatch from the vaccine strain A/Texas/50/2012(H3N2) recommended for the Northern hemisphere for the 2014/15 season. Italy, differently from other EU countries where most of the subtyped influenza A viruses were H3N2, experienced a 2014/15 season characterized by an extended circulation of two influenza viruses: A(H1N1)pdm09 and A(H3N2), that both contributed substantially to morbidity. Within the context of the existing National sentinel influenza surveillance system (InfluNet) a test-negative case-control study was established in order to produce vaccine effectiveness (VE) estimates. The point estimates VE were adjusted by age group (<5; 5-15; 15-64; 65+ years), the presence of at least one chronic condition, target group for vaccination and need help for walking or bathing. In Italy, adjusted estimates of the 2014/15 seasonal influenza VE against medically attended influenza-like illness (ILI) laboratory-confirmed as influenza for all age groups were 6.0% (95%CI: -36.5 to 35.2%), 43.6% (95%CI: -3.7 to 69.3%), -84.5% (95%CI: (-190.4 to -17.2%) and 50.7% (95% CI: -2.5 to 76.3%) against any influenza virus, A(H1N1)pdm09, A(H3N2) and B, respectively. These results suggest evidence of good VE against A(H1N1)pdm09 and B viruses in Italy and evidence of lack of VE against A(H3N2) virus due to antigenic and genetic mismatch between circulating A(H3N2) and the respective 2014/15 vaccine strain.
authors.affiliation: Istituto Superiore di Sanità, Rome, Italy. Electronic address: caterina.rizzo@iss.it.
authors.forename: Caterina
authors.initials: C
authors.lastname: Rizzo
authors.affiliation: Istituto Superiore di Sanità, Rome, Italy.
authors.forename: Antonino
authors.initials: A
authors.lastname: Bella
authors.affiliation: Istituto Superiore di Sanità, Rome, Italy.
authors.forename: Valeria
authors.initials: V
authors.lastname: Alfonsi
authors.affiliation: Istituto Superiore di Sanità, Rome, Italy.
authors.forename: Simona
authors.initials: S
authors.lastname: Puzelli
authors.affiliation: Istituto Superiore di Sanità, Rome, Italy.
authors.forename: Anna Pina
authors.initials: AP
authors.lastname: Palmieri
authors.affiliation: Dipartimento Scienze biomediche ed oncologia umana, Università degli Studi di Bari Aldo Moro, Bari, Italy.
authors.forename: Maria
authors.initials: M
authors.lastname: Chironna
authors.affiliation: Dipartimento di Scienze biomediche per la salute, Università degli Studi di Milano, Milan, Italy.
authors.forename: Elena
authors.initials: E
authors.lastname: Pariani
authors.affiliation: Governo della Prevenzione e tutela sanitaria, Regione Lombardia, Milan, Italy.
authors.forename: Alessandra
authors.initials: A
authors.lastname: Piatti
authors.affiliation: SeREMI ASL AL, Servizio Riferimento Regionale, Epidemiologia Malattie Infettive, Alessandria, Italy.
authors.forename: Donatella
authors.initials: D
authors.lastname: Tiberti
authors.affiliation: Ospedale "Amedeo di Savoia"- Torino, Italy.
authors.forename: Valeria
authors.initials: V
authors.lastname: Ghisetti
authors.affiliation: Servizio Sanità pubblica, D. G. Sanità e Politiche sociali, Regione Emilia-Romagna, Bologna, Italy.
authors.forename: Roberto
authors.initials: R
authors.lastname: Rangoni
authors.affiliation: Dipartimento di Scienze Biomediche, Biotecnologiche e Traslazionali, Università degli Studi di Parma, Italy.
authors.forename: Maria Eugenia
authors.initials: ME
authors.lastname: Colucci
authors.affiliation: Dipartimento di Scienze Biomediche, Biotecnologiche e Traslazionali, Università degli Studi di Parma, Italy.
authors.forename: Paola
authors.initials: P
authors.lastname: Affanni
authors.affiliation: Dipartimento Scienze biomediche ed oncologia umana, Università degli Studi di Bari Aldo Moro, Bari, Italy.
authors.forename: Cinzia
authors.initials: C
authors.lastname: Germinario
authors.affiliation: Istituto Superiore di Sanità, Rome, Italy.
authors.forename: Maria Rita
authors.initials: MR
authors.lastname: Castrucci
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D016022:Case-Control Studies; D002648:Child; D002675:Child, Preschool; D006801:Humans; D007223:Infant; D053118:Influenza A Virus, H1N1 Subtype; D053122:Influenza A Virus, H3N2 Subtype; D009981:Influenza B virus; D007252:Influenza Vaccines / Q000627:therapeutic use*; D007251:Influenza, Human / Q000453:epidemiology* / Q000517:prevention & control*; D007558:Italy / Q000453:epidemiology; D008875:Middle Aged; D018571:Sentinel Surveillance; D055815:Young Adult
chemical_list: D007252:Influenza Vaccines
keywords: Influenza; Test negative case–control studies; Vaccine effectiveness