Kissling, EstherValenciano, MartaPozo, FranciscoVilcu, Ana-MariaReuss, AnnickaRizzo, CaterinaLarrauri, AmparoHorváth, Judit KrisztinaBrytting, MiaDomegan, LisaKorczyńska, MonikaMeijer, AdamMachado, AusendaIvanciuc, AlinaVišekruna Vučina, Vesnavan der Werf, SylvieSchweiger, BrunhildeBella, AntoninoGherasim, AlinFerenczi, AnnamáriaZakikhany, KatherinaO Donnell, JoanParadowska-Stankiewicz, IwonaDijkstra, FrederikaGuiomar, RaquelLazar, MihaelaKurečić Filipović, SanjaJohansen, KariMoren, AlainI-MOVE/I-MOVE+ study team2018-02-232018-02-232018-06Influenza Other Respir Viruses. 2018 Jul;12(4):423-437. doi: 10.1111/irv.12520. Epub 2017 Nov 101750-2640http://hdl.handle.net/10400.18/5062I-MOVE/I-MOVE+ study team - Portugal: Verónica Gomez, Ana Paula Rodrigues, Baltazar Nunes (Departamento de Epidemiologia, Instituto Nacional de Saúde Dr. Ricardo Jorge, Lisbon, Portugal); Pedro Pechirra, Paula Cristóvão, Patrícia Conde, Inês Costa (Departamento de Doenças Infeciosas, Instituto Nacional de Saúde Dr. Ricardo Jorge, Lisbon, Portugal).Background:During the 2015/16 influenza season in Europe, the co-circulating influenza viruses were A(H1N1)pdm09 and B/Victoria, which was antigenically distinct from the B/Yamagata component in the trivalent influenza vaccine. Methods:We used the test negative design in a multicentre case–control study in twelve European countries to measure 2015/16 influenza vaccine effectiveness (VE) against medically-attended influenza-like illness (ILI) laboratory-confirmed as influenza. General practitioners swabbed a systematic sample of consulting ILI patients ainfluenza Vaccinend a random sample of influenza positive swabs were sequenced. We calculated adjusted VE against influenza A(H1N1)pdm09, A(H1N1)pdm09 genetic group 6B.1 and influenza B overall and by age group. Results: We included 11,430 ILI patients, of which 2272 were influenza A(H1N1)pdm09 and 2901 were influenza B cases. Overall VE against influenza A(H1N1)pdm09 was 32.9% (95% CI: 15.5-46.7). Among those aged 0–14, 15–64 and ≥65  years VE against A(H1N1)pdm09 was 31.9% (95% CI: -32.3-65.0), 41.4% (95%CI: 20.5-56.7) and 13.2% (95% CI: -38.0-45.3) respectively. Overall VE against influenza A(H1N1)pdm09 genetic group 6B.1 was 32.8% (95%CI: -4.1-56.7). Among those aged 0–14, 15–64 and ≥65 years VE against influenza B was -47.6% (95%CI: -124.9-3.1), 27.3% (95%CI: -4.6-49.4), and 9.3% (95%CI: -44.1-42.9) respectively. Conclusions: VE against influenza A(H1N1)pdm09 and its genetic group 6B.1 was moderate in children and adults, and low among individuals ≥65  years. VE against influenza B was low and heterogeneous among age groups. More information on effects of previous vaccination and previous infection are needed to understand the VE results against influenza B in the context of a mismatched vaccine.engCase Control StudyInfluenzainfluenza VaccineMulticentre StudyVaccine EffectivenessCuidados de SaúdeEfetividade da Vacina AntigripalVacina AntigripalI-MOVEI-MOVE+journal article10.1111/irv.12520